How to get Entry-point of an executable?

I know this topic goes a little further down the road of programming, Even further I think with Qt, so I'm wondering how I can get the entry-point of a random (let's say) process, which in this case I would like to do the following.

-Create my (Entrypoint Get) program in Qt, with whatever class/library that handles this type of topic.
-Then load whatever process into my program, Then my program calculates the Entrypoint of that loaded process.

I'm not asking for someone to actually make the code for me, but rather speak up with me what are the classes/libraries that are needed to achieve this. I know PE32 for Windows is a bit extensive subject to speak about, but I would like to someone just point out what could be used in order to achieve it.

You don't have to calculate much. The entry point is usually the symbol called "main". Other than that, this is really very system-specific.