Delegating to a pool is easy and can be done in multiple ways.
The easiest is by going to https://book.io/stakepool/ and clicking on Delegate Now. This will take you to the BOOK pool on cexplorer.
On this page click on delegate and connect your wallet. Once connected you will be asked to verify the delegation.
After you’ve verified your wallet will show that it’s delegating to the BOOK pool.