To build an object from its blueprint, the blueprint must first be placed in the world somewhere, which is done by clicking on the desired blueprint from the list on the left and dragging it to the desired location in the world. The blueprint cannot overlap other placed objects or blueprints, which would cause the blueprint to appear in red and prevent it from being dropped.
The following blueprint objects must be placed on "Simple Flooring" rather than on bare ground: Crude Bench Saw, Basic Workbench, Bench Saw, Metal Workbench, Wood Router, Kitchen Table. The Simple Flooring needs to be created before those objects' blueprints can be placed upon it. You will usually need to place several Simple Floorings adjacent to one another to have enough room for several desired objects.
Once the blueprint has been placed, it may be rotated if desired by pressing key R as many times as needed. Then drop the required logs, planks, poles, etc. that are in your hands onto the blueprint, one by one, by right clicking on the blueprint. Once all of the required parts have been added, the blueprint will be replaced with the actual object.