First of all you can only transfer bitcoins to or from TradeHill if you are not on Tor. Second go to your account on Silkroad. Select how many bitcoins you want to send to Tradehill. Back on Tradehill go to deposit funds, select BTC for bitcoins, enter how many btc you want to send and it enter. Tradehill will give you a bitcoin address that will last for 24 hours. Takes about an hour for the transaction to be complete.