Navigate to the Staking page.
Click the "Create New Delegation" button.
Enter the pool ID in the "Pool ID" field.
Click the "Send" button.
Visit the Staking page again.
Select the delegation you wish to top up.
Click the "Add Funds" button.
On the next page, enter the amount you want to stake.
Click the "Send" button.
To unstake your coins, go to the Staking page.
Select the delegation from which you want to withdraw.
Click the "Withdraw" button.
Specify the amount you want to unstake.
Click the "Send" button.