I cut the 2x4's at 21" (4 of them) after I made the cuts I used the kreg jig to pre-drill the holes for the screws. After I pre-drilled the holes, I screwed the 2x4's together with 1 1/2" kreg jig screws. Once done with that I also screw on the legs. after screwing on the legs I secured the frame by adding additional 2x4's which I cut at 21" also. after completing the frame I used a mixture of half quickcrete and half mortar which I poured into a pre made melamine form and added porcelain tiles to create a unique look. I let the concrete cure for one weekend. the following Monday I took apart the melamine board and placed my concrete slab on my wooden frame to complete my project.