No problem, jt. I would be most happy to help you. The first thing yo8u need to konw is that enemas can be fun, as well as for healthy practices of cleanliness. So there are several things one needs to know to do this.
First, whether or not you go to the bathroom before your first enema is up to you. More inside makes it more difficult to take the enema, so it might be a good idea, the first few times, to empty first and then take the enema.
Second, the recipe is quite important. Electrolyte balance should be considered, and that means that you should put one teaspoon of salt in the bag per quart of water. The exception is if you use a soapy solution to do the enema. I have not heard of a requirement to use salt with the soap.
The hose you use is up to you. If the shower hose works for you, then go for it. There is nothing you need to worry about, unless it is uncomfortable for you to use the hose. But one caution I would stress very seriously: *DO NOT FORCE THE TUBE IN ANY FARTHER THAN IT WANTS TO GO!!!* Injury can be serious if you perforate your colon. So be most careful in that regard.
As for the taking itself, go as slowly as you need to do it, and go from there. If you get cramps, stop the flow for about a minute, and that will allow the colon to acclimate to the contents of your colon. Then resume, and periodically keep track of how you feel, so that you can stay comfortable with the experience.
As for quantity of water, I would go small at first, perhaps only a quart at a time, until you become accustomed to the process. Then you can increase the amount of water you take, as you get more experienced with this process.
Retention is up to you. It is usually recommended that you retain for no more than 15 minutes, as the cleaning process is dependant on getting things out early. Though I have held a lot longer than than, and that is okay, too, for me. Try it as you go, and see what happens. This should be a good experience, and can be, if you do it right for you. Your right may not be mine, and visa versa, so keep that in mind.
I hope this has helped, and if you have any questions, ask, and I shall be more than happy to answer them, or at least try to find the answers. But the most important thing is to have a good, and even a fun, experience doint this. So enjoy!!!!