How do I set up an guide layout?

[AndiGreyScale]

I apologize for the vague title, I'm just not sure how to phrase what it is I want to do.

I basically need help figuring out how to do something like this-



Not the designs in it, but the layout itself. It's all perfectly aligned and I can't for the life of me figure out how to do it in GIMP.

Something like this, in photoshop.