The main problems I see are the following:
The value in the numRight variable is wrong for two reason: The 'right' sensor is not reseted at the proper time and you read the 'left' sensor value instead of the 'right'.
The angle calculation is faulty
The half rotation is performed in the wrong direction
Here are my code comments:
//Move forward until you ...
Note: I have no particular knowledge of how monobrick work.
You're never escaping the while (true) loop. The example you're pointing too use an event-based model, and it looks like you prefer a loop. This is what you want:
public static void Main (string args)
R_Main main = new R_Main ();
You need to be using the standard MonoBrick Communication Library if you want to connect remotely to the EV3.
You would then need to have the following using statement at the top of your code:
I believe you are referencing the MonoBrick EV3 Firmware which doesn't need to connect to the brick as it is the brick.