Step 1: Once you're logged in, head over to the markets page or the portfolio page. From there, just click on the "Lend" button for the asset you want to deposit.
Step 2: Type in the amount you wish to deposit and hit the "Deposit" button.
Step 3: Open your wallet and give the deposit a quick authorization.
Step 4: You're all set! You can check out your updated holdings by visiting the portfolio page.