Very similar position to you and also pretty nervous.

It might depend on your company culture but seniors, leads, managers, etc. are there to help you. And most of them want to help you.

Provided you do some Googling first, people will want to help you figure it out or explain some code that they wrote. Just do your best to actually listen to them and write the important stuff down.

Schedule a 1:1 with a random senior or lead on your team. They'll probably accept as long as you check their calendar and find a good time for them (not during their lunch lol). Ask them questions about the system you are working on or what it was like for them to start out.