Basically it is a starbase, the white is either the ass-end of your ship visible over a pit or the fronts of a pair of docked ships (your pick), so the L-shaped area is a ledge that surrounds the pit, and the walls around go up all the way. There are a few stalls set into the walls that will offer services or trading (on the little map the green blocks would be smileys, and that top one, even though I didn't draw it that way, should be in a wall too.) Maybe there are some crates or barrels around or perhaps a railing.
But you don't have to follow it too closely, I trust your judgement. If you think of something that works better, or a layout that is easier, go for it. Maybe it might be too tough to convincingly draw the stalls as set into the walls. Maybe a big hanger door would be easier or something. Basically it just needs to be starbase, and if the window thing doesn't appeal to you, you could nix it and actually make the player navigate the board itself. But I need at least the four people to interact with: One's a trader, one sells ship services, one gives a quest, and the random guy on the dock gives information.
*POW* *CLANK* *PING*