Joint and plane the boards so that they are flat and square. Run the boards over a jointer first to create a flat bottom and feed them through a planer to give them a smooth top and a consistent thickness.
Joint the edges of the boards to make them straight. Check the fence of your jointer before you joint the boards to be sure the fence is at a 90-degree angle to the bed of the jointer.
Lay out a line of bar clamps on a flat table or work bench. The distance between the two end clamps should be a few inches less than the length of your boards.
Lay the boards together on top of the clamps so that the boards are perpendicular to the clamps. Arrange the boards in the manner that you plan to glue them together, taking the appearance of their grain into account.
Stand all of the boards except the last one on their edges on top of the clamps. Run a line of glue down each of the edges and spread it over the surface of the edge with your finger or a foam brush.
Lay the boards flat with the glued edge of each board pressing against the board next to it.
Tighten the bar clamps to press the boards together. Add another bar clamp on top of the boards in between each of the bar clamps underneath the boards. This will exert a more even pressure and keep the panel from bowing. Tighten the clamps until a small amount of glue is being squeezed out of all the joints.
Leave the panel until the glue is completely dry, at least two hours. Scrape the glue off with a paint scraper and plane the panel smooth.