REMOTE CONNECTIONS

(1) SOME ONE SHOULD KINDLY HELP ME SOLVE THIS PROBLEM.

I AM TRYING TO CONNECT TWO REMOTE OFFICES TOGETHER USING TWO DSL MODEMS ONE ON EACH SIDE AND TWO WIRELESS ROUTERS ALSO ONE ON EACH SIDE.THE TWO PLACES CAN BOTH BROWSE THE INTERNET.I WANT TO CONNECT THE TWO LOCATIONS VIA THE ROUTERS SO THAT THEY CAN SEE EACH OTHER FOR FILES/DATA TRANSFER REAL TIME OR ON LINE.
HOW CAN I ACHIEVE THIS AIM? THANK YOU.
PLS VERY URGENT.

(2) I WILL LIKE TO CONVERT AN EXISTING WINDOWS XP PRO WORKGROUP COMPUTER TO A ‘DOMAIN’ TO RESTRICT SOME USERS WITHOUT LOOSING FILES ON THE TARGET COMPUTER