How to join a mining pool? I'm running a Bitcoin node on my computer.
Can I configure it so I can join a mining pool?
If so, how to do this, or where can I find the documentation?
To join a mining pool go to their website and create an account. Connect the ASIC machines (which you already bought) to their server using the stratum link they give you.
The mining pool has its own bitcoin nodes which will be used for mining. There is no way to connect your node to the pool - they don't want to use it. Your bitcoin node is only used for your mining if you run your own pool.
Miners just do the work the pool asks them to do, without knowing which blocks they work on.
In theory miners could use their own bitcoin nodes for a couple things:

You could verify that the mining pool is mining on the longest public blockchain. If you detected that this is not the case then you could automatically switch to another pool. This would ensure that you never assist a pool in performing a 51% attack.
If the pool allows you to mine with getblocktemplate instead of the stratum protocol then you could control which transactions go into the blocks you mine (if the pool allows this). Your bitcoin node would give you transactions to put in the blocks.

But in practice noone is doing either of these things.