Run an app in windows form

Question

Hi guys, Now I have to write a program, that call an external app, that must run in a windows form of my program. For example, I call the Calculator or Paint and it will show only on a form of my program (such as frmMain). By the way, I want to know that how to touch a event of mouse click of system when my app not actived. I want to ask if anyone can help me. Thank you.