So I Googled with no results. I mean how should we split the code, ie who codes what? Do we both take a script here and there or how? (PS: there are only 2 of us). I just wanted to know from people with more experience in the field than we have.
You code a project with one or more other programmers by dividing the task at hand. Regardless of how you program (structured or object-oriented), you can section any project in modules. A savvy software architect will lay out the project design based on the objectives and requirements, identify potentially reusable sections that he/she will attempt to modularize to obtain such reusability, and then you an start assigning pieces of the project to the different programers.
The resulting source code may or may not belong to a single binary and there are source control websites and products (like Subversion) to keep track of what everyone is doing.