Handstand push ups are an advanced level exercise but can be modified to accommodate novice or intermediate lifters.
The easiest way to do handstand push ups is to prop yourself up against the wall [as a spot] eventually you'll want to increase your range of motion by placing your hands on boxes and lower your head between them. This is the ultimate pressing exercise and should be included for some massive shoulder development and full body strength and athleticism.
Patience is a must.
