Add solution to enema bag mixing with warm filtered water to achieve desired amount.
Suspend enema bag approximately18 in. above the  rectum. A good tool for this is the  IV Stand for Enemas
If you need better flow control of the enema solution.  The ramp clamp is what you are looking for.
   Knee-chest position with chest against floor and rectum higher than head this is a best position to receive an enema.
Insert nozzle/rectal tube tip into anus, using a lubricant (Super Salve Surgilube  Vaseline 13oz.)as needed. Anal lubrication is very important.
Inject solution into rectum and colon slowly, and take as much as possible , refill bag if needed or until it becomes uncomfortable to take any more solution. Massage abdomen in counter-clockwise direction this will help the solution higher into the colon and break loose any encrusted material.
  When bag is empty or no more fluid can be injected remove nozzle/rectal tube. If you have trouble retaining the nozzle you might want to try a retention nozzle if you are having trouble retaining the solution or both. 
Some people prefer to use a retention plug after they received their enema solution and removed the nozzle/rectal tube.
Lie in each position for a few minutes, while massaging abdomen Enema Positions
Now you can move to the toilet and release the enema.

 Wash and sanitize Enema Equipment after use

When expelling the enema:
You can massage the abdomen in a clockwise direction this will help move the solution back toward the rectum and anus.

Massaging the abdomen while expelling the enema helps move the enema solution and  gas and feces toward the rectum and out the anus.

The best position for expelling your enema is squatting over the toilet not sitting on it. The squatting position puts pressure on your abdomen from your thighs.

In many countries, toilets are made so that people squat when they move their bowels. The Welles Step positions your body so that you are squatting when you sit on the toilet. Squatting,  supports the abdominal wall and the bowel as we bear down, brings about an easier bowel evacuation in this way.
People who use the Welles Step tend to have fewer hemorrhoids, hernias,  anal fissures, varicose veins and use less laxatives.
It fits under the toilet when not in use.