Step 6: Assembly (3 of 3): Adjustable Top
First, attach the bottom with the supports with 2 1/2 inch wood screws (recommended to pre-drill the holes). I put 2 screws in each side. See the picture for how I used clamps to keep it all in place.
Next, slide those pieces into place and clamp the Top of the 'Top Assembly' to the rest of the saw horse while also clamping the Top Supports so they don't move while drilling holes through the Top.
(See the pictures for more detail)