The main part of the block is what is connected to the standard Bravo steering ram mount. This is what I think you are talking about. In a single, you just connect the R & L from the helm into either the top or bottom connections and cap the other two. These connections are basically just a tee to make it easy to connect the second drive. The plugs in these connections may have small speedi-bleeder valves in them to help in getting air out of the system. You can connect small hoses to them and run the hoses back into the cap of the reservoir, crack them open, and slowly turn the wheel back and forth to remove air. Do not confuse the side hex fittings as plugs, they are relief valves and there is no reason to touch them.
Hope I helped out!