You're the only gymnast on these forums I'm aware of although there are probably others, but maybe you could help me with this.

I want to be able to do a 'midstance', I'm not sure if it's the correct word but it's like when you lift your entire body of the ground and are only supported by your hands which are kind of under the hips. I tried it at home but I'm unable to do it.

What should I pay attention to?

Thanks in advance.

Do you hold it? And, does it end up looking similiar to the figures in the following image? http://drillsandskills.com/images/display?path=planch.jpg

If so, you're talking about a planche, which is easiest to do on parallel bars (or any two stable raised bars shoulder-width apart), more difficult on the floor, and most difficult on the rings.

According to the book Rings: Methods, Ideas, Curiosities, History by Ivan Cuk and Istvan Karacsony (citing my source), in order, the most active muscles are: deltoids, pectoralis major, teres major, spinal column extensor muscles, gluteus maximus, abdominal muscles, tricep brachial, wrist extensors, quadriceps femoris, biceps femoris.

You should work a lot of straight arm extension work, in the manner of a front raise, both standing and lying down.

Check out the planche progression exercises here: http://www.dragondoor.com/cgi-bin/articles.pl?rm=mode3&articleid=229

The muscles used in a maltese are similar to the ones used in a planche. Pay particular notice to the dumbbell drill in the following link (lowering the weight over your chest to a 45-60 degree angle is the planche variation): http://www.american-gymnast.com/tt/strength/maltese/index.htm

Additionally, you'll need to greatly enhance your core strength (both dynamic and static) and ability to maintain a slightly hollow body position. You should work on getting a solid handstand as well as incorporating static exercises into your ab training (particularly hollow holds, hollow rocks): http://www.drillsandskills.com/skills/cond/core
http://www.american-gymnast.com/tt/tc/handstand/index.htm

Hanging knee-hip and (once you're strong enough) straight leg raises are excellent for ab strength: http://www.exrx.net/WeightExercises/RectusAbdominis/WtHangingLegHipRaise.html
http://www.exrx.net/WeightExercises/RectusAbdominis/WtHangingStraightLegHipRs.html

At this point, you should concentrate on building your shoulder and core strength. Once you've significantly improved, continue improving and start incorporating the planche progressions. Depending on where you are you could have your planche (with dedicated training) in six months to a year.

The planche is a C skill on a scale of A to E, so it is not easy. You won't find many gymnasts that can do it until you get into the upper levels approaching elite. To see a list of floor skills and their difficulty ratings, check this link out: http://www.drillsandskills.com/skills/Floor/