mmm I have to do it all by myself! Q.Q an operator trained at home should come and install the program for you and then start it while you make him coffee as a kindness, then maybe he could scratch your shoulders while trying the program U.U
i have win 7 and i have never put a password to the pc ... you should leave it blank ... but there are many types of passwords, those of the network, browser, pc and even vnc, i have no idea which password is required, vnc once installed asks you to enter a security password.
This program may not be for you. Every problem you have had could have been solved with a few minutes of review of this thread and perhaps a Google search. Lots of other fun stuff to do with a 3DS. Consider looking into them.