If your university offers a course teaching C, that might be something to consider.
If you are planning to self-study, it is best to use a good book. I recommend the C Programming Language book by K&R. You should use the second edition however (the second edition is available online for free as well).
You can also try
https://www.cprogramming.com/ or "Learn C The Hard Way" (
https://c.learncodethehardway.org/book/, although I rarely endorse online websites.
If you end up using "Learn C the Hard Way", I suggest not listening too much to the opinions of the writer (Zed Shaw). He's an opinionated man who has, to say the least, opinions which are significantly different from the rest of the computer science community.
