You can deposit SOL for trading fees on your Phantom wallet. If you don't have SOL yet, you can purchase SOL on an exchange and withdraw SOL to your Phantom wallet.
You can then swap any asset in your wallet for USDC within the Phantom interface itself, or on Raydium.
Navigate to our alpha on mainnet. On the top right side of the page, select "Connect Wallet."
Click on "Deposit" and choose the amount you want to deposit. Click the maximum you want to deposit and enter it into the form.
If you want to withdraw from Drift, click on "Withdraw" and choose the amount you want to withdraw. Click the maximum you want to withdraw and confirm.