How to find the starting address of an application for memory editing a process?

Question

I want to know how to find the valid addresses of an application from beginning to end because I want to know how to memory edit an application for example Notepad. Do I have to decompile the application and see the assembly code or machine code. Because I see people always making mods for applications like minesweeper and some PC video games.

P.S. I will be using the programming language C# and Win32 functions to perform the memory editing.

Answer 1

To find the start and end addresses for a process

Process proc = Process.GetCurrentProcess();
IntPtr startOffset = proc.MainModule.BaseAddress; 
IntPtr endOffset = IntPtr.Add(startOffset ,proc.MainModule.ModuleMemorySize); 

http://www.ownedcore.com is a good resource to learn about memory editing.