What are my next steps?

Hey all, after playing Arena for a few weeks, I visited my local card store for their weekly Commander night. I bought a pre-constructed deck (Nelly Borca) and played some casual games with another newcomer and two experienced players with casual decks.

It was tons of fun and I want to fully commit to the game. So the question is, what should my next steps be? Should I work on my deck? If so, how do I know how to improve the deck? Should I just keep playing with my current deck? Should I watch games online?

Any advice would be greatly appreciated! TIA