These instructions are for a ramp that is 8' x 5'. Material quantities will vary for ramp sizes bigger or smaller.
Using a speed square, make a vertical line on the 2x8 evenly with the front edge of the cap blocks (Image 1). From the top edge of the vertical reference line, mark a line 90 degrees back towards the building on the 2x8 (Image 2).
For reference, this line should read as level with your 4' level.
Put the 2x8 back in place. The top of the board should align with the bottom of the building. Using a torpedo level, mark a vertical line on the 2x8 (Image 1), and cut off a small piece with a circular saw (Image 2). Cut three more 2x8s using the already-cut 2x8 as a guide.
Put the assembly in place around the 4x4 posts and flush with the building. Level the 5' 2x8 ledger board with the bottom of the building (Image 1), and temporarily secure side joists to 4x4 posts with a deck screw (Image 2).
If you want to attach the ramp to the building, create a nailer below the bottom of the building. It is ok to leave this assembly free standing if you choose.
Secure decking of choice (We used 2x6s) on the ramp starting at the building and working your way down using two deck screws per board at each joist. Cut off excess overlap, and use the remaining piece for the next run.