after buy, Skype, iBooks, etc, Apps from itunes, not startup after click, well

this is my first time run external Apps[unsuccess].

ALL builtin Apps are starting properly, but ALL installed after buy, Skype, iBooks, etc, Apps from itunes, not startup after click, well? when click screen goes out and come in like was, app not startup.

I tried but didn't work...that I did is download app to desktop PC(itunes) and after sychr with ipad, is that correct?

how I "restore the ipad off the computer/itunes program. " ?

another Q: after press "home" all current processes shut down?