Use an existing furniture piece such as an old dresser, small bookshelf or buffet for the basic frame. This furniture piece does not have to have all of the elements the final credenza will have, but it will be faster than building it from scratch.
Use wood glue to attach the top, bottom and sides of wood together to form the long, rectangular structure of the shelves. Trim the shelves to size and use a nail gun to nail them in place. Add legs if you prefer. If you are using a recycled piece of furniture, use a table saw to cut wood or medium-density fibreboard to size for the shelves. Screw the shelf to the wooden frame that previously held the drawers in place.
Trim the wood to the desired size of the drawer. Set the thickness of a dado blade to 1/4 inch to add slits, or dadoes, to the front edge and back edge of the drawer sides. The dado blade is part of a table or radial-arm saw. Cut a tongue in the end of the front and back panels to fit into the dadoes. Cut more grooves in the front and sides to fit the bottom of the drawer. You will have a dado on each side of your drawer.
Place two metal slides on the inside of the credenza. Screw the slides into the credenza with mounting screws. Add metal glides to the sides of your drawers so they will slide on the track you installed.
Add small holes to the back of the credenza. While the TV will sit on top, the holes will accommodate wires that may run to various devices such as a gaming system or a DVD player.
Stain the credenza in the color of your choice. Replace the current drawers with sleek sliding doors to add convenience and a modern touch. Acrylic panels and translucent plexiglass are two other options for the front.