Just take Harvard's CS50x on edx. It's probably the best intro to programming online and primarily uses C. Depending on your university's CS program, it might

Just take Harvard's CS50x on edx. It's probably the best intro to programming online and primarily uses C. Depending on your university's CS program, it might cover the equivalent of 2-3 semesters' worth of material without feeling like drinking from a firehose. If you already know how to program, then you could just pick up K&R and work through it.