Not sure if will show up - but need help on cleaning filter

Hi guys.

If you can see this, please help. I don't have the money for pool maintenance service and my filter is all clogged up with sticks.

I have a hayward pool star filter. It is a big silver canister with 4 plastic filter elements. I have a pool pump attached to it that is new. This guy I was paying to do my pool for a while attached it and it is 1.5x as powerful as the original. I can't find anything specific to this filter on their site though.

There is a clear plate area and I can see that it is full of sticks but I can't open it. There is also a big warning saying "release pressure before opening!".

It's been clogged a couple of days now and I can't get any response from this guy and I don't want to have to drain the pool.

So on the big metal canister there is some kind of valve and pressure gauge. The gauge reads zero but I can't figure out how to open up the valve itself of if that's what I want.

There is also a spigot attached to a pipe coming off of the big metal canister. There is a sprayer type thing on here. I remember vaguely from a long time ago that this was important and could be used for relieving pressure or something or so I think. But I can't get the faucet to turn and one of the parts of the handle already broke off.

Is there a checklist or instruction list somewhere that can help me to do this safely?