As others have noted, wall push ups are a great way to build upper body strength. Another way to do push ups is with a table. Try table push ups too.
Are you doing plank ? Another good exercise to help you do military style push ups is the plank. If you can't hold plank on your hands, try modified plank. www.sparkpeople.com/resource/exercises.asp
Don't forget the old cliche,"how do I get to Carnegie Hall ?" Answer ? practice, practice, practice.