Welcome, John
Here's an easy way:
1. Download a light client here:
https://github.com/bitshares/bitshares-2/releases2. Create an account and set a secure password
3. Click the gear icon in the upper right to get to Settings, then click 'Wallet Management Console' button at the bottom
4. Click 'BACKUP BRAINKEY' button and enter the password from Step 2 to reveal it. Write it down and keep it safe. Done!
At this point, you could completely delete your wallet (using the Wallet Management page) and uninstall the light client, if you wish to only deposit into this account and NOT send. If in the future you need to access your funds, you can re-install the light client (or simply use a web wallet) and enter your brain key to recover your wallet/account.
Or, you could save a wallet backup--just make sure to save the password too.
But I recommend saving the brain key either way to be on the safe side.