How to divide a part to apply different materials on it?

[Serenyx]

Hello,

I have a part similar to a cube, and I need to create different areas inside of it, so I can apply different kinds of materials on the volumes created.
I've used the Sketcher tool on one surface to draw to lines I need to divide those areas, but then I don't really know which tool I could use.
I was told it would be easier to work with "cut surfaces" (I don't know if that makes sense in english), but then again I'm a bit lost here.

If you have any idea about what I could do, I'll take it

Thanks!