In order to lock your liquidity, head to the Locker page. Once your token has been approved, you'll find a locker for your token. Click on Enable contract first, then click on Manage lock.
Choose Lock LP for your first lock.
Select the amount you want to lock, set the expiration date, and click Lock.
Congratulations, you are all set!
Your token will be added to the swap list, and your lock will be shown to the users in the info card.