These measurements are an approximate. What you will need will depend on the size of truck you build your rack for. It's best to take measurements and go off of those. It's always good to have a little mor lumbere than you need.
What you will need for supplies:
14 feet 2x6 or 2x4 boards
24 feet 2x2 boards
Have a bunch of screws that will be the length to hold together your lumber.
You could do this all with hand tools if that's all you have but power tools make it so much easier.
Saw- for cutting lumber.
Drill- for putting in screws.
Measuring tape- for finding out your measurements.
Square or at least a ruler- for getting angled.