Yesterday it was my first day at work ever. Basically I have no tasks yet, all I can do for now is look at other's code and figure out the basic of how their framework works. Is it usually like that?

Yes. First day for new people here is usually just setting up hardware, OS and tools to preference. First week is code reading and maybe fixing a few simple bugs.

Doesn't matter if someone is junior or senior, new code is big and scary, just dive in and get acquainted with parts of it, play around a bit, use Google for unknown technologies, use coworkers for targeted questions about the business logic.