This would be the way I'd attack it.
Decide what types of reports you want to write. Company specific (which can be initiation or post-news updates or quarterly)? Sector?
Read a ton of reports. You can usually get sellside spam direct from banks, or through your broker. Otherwise I assume the library can help. You want to learn about how to structure it, what kind of things analysts will generally highlight, the kind of language they use around them, as well as a ballpark for how shitty your numbers are compared to the pack.
Goes without saying, but at some point you need to know how to do a DCF. You can start off just learning about the company, the strategic environment, SWOT/etc, and using financial metrics from other reports, but eventually if you want to learn how to do it for yourself, you need the building blocks. It's a fucking complex topic and you quickly figure out how much you don't know. The two to check out would be
You could also get by with some old CFA textbooks, but they are dense af.
This is a super valuable exercise if you plan to work in the field. Being able to build a three statement model and walk through it is question one for every grad program.
After you figure out that part, you can start looking for where your opinion differs from everyone else's. That's where the value in your analysis comes from. Just make sure it's different for the right reasons :)
Good luck!