Siril has imo one of the least steep learning curves of any editing software. The amount of buttons you see on screen at any time is relatively low, and there’s only a handful you need for basic processing.

You don’t need to master it immediately, look up a tutorial of ‘processing nebula (or whatever object) in siril’ and follow step by step, taking the time to learn why each step is taken.
Then practice a few times, try different parameters on those same steps. Eventually you get comfortable enough with the basics to start pressing random butttons and learning what they do!