Open your wallet, then go to: Tools -- Debug console.
In console write:
addnode 107.172.9.103 add
addnode 72.11.129.12 add
addnode 107.172.6.82 add

Or you can add nodes through the .conf file, as well descriptioned here:
http://pos-monkey.com/how-to-add-nodes-to-sync-wallets/