Gather the tools and materials. Some stages you can build and take to the site. Other stages are best built at the site. Make sure you have all the materials and the tools that you need.
Measure the stage area. A typical small concert stage will be 8 feet by 8 feet. This can be built in two sections of 4 by 8 and then assembled with bolts. There are exceptions. Some venues will require smaller or larger stages. The height requirements might vary as well. As a rule a thumb, 1-foot legs will be all that is necessary.
Cut the pieces, which include the frame, the plywood stage, and the legs. Use 2 by 4s for the legs and frame. Mark the measurements on the wood and cut with a circular saw. Use a work bench or sawhorses and allow the wood to drop freely.
Assemble the frame and decking. Set the frame in place and drill holes where the corners connect. Use a nail gun to connect the corners together. Use six 2 by 4s to make the frame. Place one 2 by 4 in the center to make the frame secure. Align the plywood on top of the frame and screw it in place with a screw gun. Screw the corners in place first. Once all four corners are secure, find the centerpiece 2 by 4 and secure with screws. Then screw the rest of the deck, spacing the screws about one foot apart.
Attach eight legs to the frame. Start with the legs on each of the four corners. Drill a hole in the frame and the leg. Place the leg on the inside corner. Use a 1/2-inch bolt with a washer to attach the leg to the frame. The washer provides a smooth surface for the bolt and will prevent it from coming loose. Tighten with a socket wrench. Center the four additional legs between the four corner legs. You will have three legs on each side,
Connect the two sections. The two sections will be bulky and heavy. Get a couple of friends to help you put them in place. Once the two sections are aligned secure them with bolts.
Decorate the stage so it doesn't look like the rough piece of wood that it is. You can paint it, lay deck flooring on top of the plywood or use carpets to make a nice stage.