(1) Drill 4 -5 holes in the steel pipe that are big enough for your screw's post to pass into, but not so big that the screw's head can pass through it. Space the holes about 2" from each end and aboout 4' intervals. Since I purchased mine from a fencing company, they drilled the holes for me.
(2) On one side only, enlarge the holes with the drill large enough to pass the whole screw head through.
(3) Using the 4" common nails, Take the 2" x 4" x 12' and mount it length wise with the 2" x 6" x 12' making a 'T' shape ( see diagram). I recommend nailing every foot, but more would also improve the rail's durability.
(4) To mount the rail, you need to place it on the top edge of the 2" x 6" (see diagram). Then, using a screwdriver, mark out where the holes of the pipe are. Using the marks as a guide, drill holes to start your screws, or use the common nails to get your screws started. Use the wood screws to mount the pipe.
(5) Rip that bad boy up! Have fun and skate safe.