First, let's make sure we all know what the entire lower colon looks like, and what the names are for each section :
In a typical enema, 1 quart (or less) of solution is inserted into the sigmoid colon and expelled (as in a coffee enema, or other therapeutic enema).
On the other hand, the typical goal of a high enema (2-4 quarts of solution, or more) is to cleanse the ENTIRE colon (the other reason we would want to place fluid/solution higher than the sigmoid colon would be to allow us to hydrate & nourish/medicate ourselves if that cannot be accomplished via mouth).
How in the WORLD could I get fluid into the transverse and ascending colon? GRAVITY will be your friend here, as well as massage.
First things first, this will obviously work best if you've recently had a bm, or have done a low-enema to remove the fecal matter from your sigmoid colon (after a coffee enema is good).
Although this first way is likely the most effective & quickest overall, it also takes some practice (and being VERY in tune with your body, as well as being very careful!)
If you have a long enough, soft/flexible enough tube attached to your enema bucket/bag (and a lot of patience) it is very possible to work the tubing past the corner of the descending/transverse colon, so that the solution is dumped into the transverse colon instead of the sigmoid. This is done by pushing the tubing up 12-16" until it will go no further, releasing a bit of solution, while "twisting" and gently pushing the tubing (just the way you'd push soft tubing around any 'corner'. Utmost care must be taken while doing this as to not damage the tissue or wall of the colon). When doing a high enema like this you would lie on your right side, so the fluid would naturally travel toward the junction of the transverse/ascending colon, and then you would massage it around the corner (when doing this kind of massage, just imagine that you're pushing a water balloon through a tube smaller than the water balloon...no "pushing with the fingers", but rather digging in deep with your entire hand, and shoving the 'water balloon' along :)
After you've inserted the first 2 quarts, you will need to refill your enema bucket. Generally you can handle this by yourself (if you get all your ducks in a row and everything properly positioned), by having another container of solution 'at the ready', sitting up slightly and pouring it into your bucket. Obviously, the easiest way is to have someone do it for you.
The most typical way to do a high enema to NOT try to manipulate the tubing around the corner of the descending/transverse junction, but rather to insert the tubing comfortably, changing your position and massaging the fluid throughout the colon. To do this, you want to place the enema bucket a bit higher (so the solution will flow with more force), and you would lay on your back with buttocks elevated (a slant board is perfect here, because you wouldn't be bending at the waist and possibly constricting the flow of the solution). OR you can assume the 'doggy style' position, resting your weight on your elbows forearms, with buttocks elevated). Either of these positions will cause the solution to flow (gravity) to the junction of the descending/transverse colon...and you'll be "water ballooning" it around the corner as it flows in. You should try to get the first 2 quarts in like this, before changing positions and rolling on to your right side...but sometimes rolling onto your right side will allow you to get in the last of the first two quarts, so don't hesitate to 'roll to the right' whenever you feel you're ready.
Note, at ANY time you sense cramping or the urge to expel, simply clamp of the tubing/flow and do strong, rapid deep breathing (I find 'through the nose' to be most effective, but some find panting through the mouth to be). The first few/several times you do this (especially if you're an "enema newbie"), you may need to expel and start again. No worry, it's just part of the learning curve - it doesn't mean anything is wrong with you.
Once on your right side, start with the final 2 quarts (or as much as you can hold, when first learning). Continue allowing the fluid to flow in...and don't hesitate to 'work with gravity'...if you feel it would be more effective 'doggy style', then switch back to that position to get more fluid in, while continuing to massage it around the corners.
The more solution you can get it, the better! If you're able to get in more than a full quart on your first try, consider it a success! If you're able to get in TWO quarts on your first try, that's pretty amazing. And if you can get in more than 2 quarts on your first try, well then...we don't want to hear about it! (lol) Of course we want to hear about it...and please share how/what you did :)
The herb catnip is VERY relaxing, so adding some catnip tea to the solution would be beneficial. Remember, you'll likely be assimilating a LOT of plain/empty water into your bloodstream (which can imbalance electrolytes temporarily); using a solution of a weak herbal tea would be very beneficial (particularly an herb like comfrey leaf that's ultra-high in minerals/nutrients).
How long do you retain the solution. As long as you can or would like to :)
And lastly, if you are able to get enough solution into your lower colon and a substantial amount down the ascending colon to the cecum, you may experience what is known as a "cecum flush". I've never experienced it (grrrr), but what happens is a major colon contraction starting at the cecum that supposedly empties the colon entirely. That'd be SO cool (and SO cleansing for sure). So if that happens, don't freak out...let us know, and you can have the very first virtual "Cecum Flush" T-shirt and award on CZ! :)
And of course, after doing a high enema, expect your bowel activity to slow until your colon can fill back up.