Click 'Wallet' in the main menu and then select the desired coin. That will take you to the balance page of that coin. In the bottom you will see several panes, including but not limited to: Deposit, Withdrawal, and Transactions. Select the 'Deposit' pane to see instructions on how to deposit funds. For example, this is the BTC deposit pane:

Here you can generate a deposit address that you can use to deposit funds in SouthXchange.