create a cannon ball based on cannon angles and cannon power

I am trying to make a 3d version of a game I made long ago with a different program.

the game requires a cannon to fire cannon balls at a castle.

since I am working with a new program and working in 3d I have no clue how to get this working.

I can't even get the add force thing working with a ball because c# is so confusing to me right now.

I try searching for tutorials and examples but everything is out of date and only gives errors when I copy word for word.

If anybody can help me out here that would be really great.