Create Simple Layout in CSS, picture to guide you

I need a simple CSS template made based on the attached image. I'm not worried about colors or text, just the positioning of different DIVs or SPANs or whatever you choose to use (other than tables). I'd like the positioning to match the attached picture (not literally exact proportions, it's just a rough sketch). The picture has text that refers to another designer I spoke to before coming to this site (he's too busy). The four yellow boxes on the bottom represent one row - but I'd like to be able to easily add more rows exactly like it directly below, stacking 4 boxes on top of 4 boxes on top of 4 boxes on top of ...etc... if need be. Needs to match the picture in common browsers/versions.