Sketch out the basement floor space as it is now and how you want it to be. Measure the space that your want to use, and plan where its various features, including the wet bar, will go. Consider making the wet bar a focal point of the room, perhaps taking up a whole wall.
Fix any moisture problems in the basement and seal the walls. Run new wiring for lights and a refrigerator in the bar, along with plumbing for the sink. Add framing, insulation and drywall. Put in a ceiling, using either drywall or ceiling tile. Prime and paint the walls.
Build the wet bar framing, using 2-by-4 lumber. Cover the framing with cherry veneer, and install cherry cabinets. Build a countertop covered with black marble tiles. Leave an opening for a sink. Plan to use a kitchen sink if the bar space is large. Decide where your outlets will go.
Complete your bar space. Secure a large mirror for the wall behind the bar. Buy four or five stools. Install a refrigerator, ice maker, wine rack and shelves for glasses and liquors.
Put in your flooring last. Lay black and gold tiles. Consider using a diamond pattern.