- how to abbysals work?
- can i use the gnosis in it?
Abyssal Deadspace - EVE University Wiki would be a good place to start, there are several YT tutorials also. You can’t use a Gnosis, as it’s limited to cruisers, and the Gnosis is a battlecruiser* as others pointed out. 
The Gnosis is a battlecruiser and cannot enter abyssal sites, which are limited to cruisers, groups of two destroyers or three frigates.
Other than that, the wiki and youtube links is indeed a good place to start!
You need a filament in a Cruiser in deadspace.
Jump into the first pocket, destroy all enemy vessels in that pocket, so the gate to the next pocket can be used.
There’s three pockets.
If you don’t manage to jump through the last gate home within 20 minutes, the space collapses and your ship and your capsule will be destroyed. If your ship is destroyed by NPCs, your capsule will be killed as well.
So don’t fly what you can’t afford to lose and look for a player owned station where you can jump into a naked clone without time restrictions.
That’s a brief description, the link posted above is very helpful for further information.
Perhaps there was a change in rules, but the filaments only allow Frigates, Destroyers and Cruisers. If you want to solo in a Destroyer, you still need 2 filaments of the same kind.
No you can not use a gnosis inside of a Abyss
Bro have you ever done an Abyss it only allow frigates, Destroyers, and cruisers
is the gnosis in that group?
Even though it’s obvious, worth pointing out. Don’t forget to grab your loot after clearing the room.