Yes I second the rec for lessons. There are specific exercises which, practiced daily, will help you extend range and find the many things your voice is capable of without damage. There is really a lot to it. I play several instruments (guitar, clarinet, sax) reasonably well but singing was the longest journey for me. I started lessons some years ago, stopped, started again, and in the last year or so I find I have a voice that I can really use. It's been a big work, but well worth it.
There are so many small recommendations that people could make, but without actually hearing you it doesn't mean much and could even push you in the wrong direction. There is one thing I can say though. If it hurts or feels uncomfortable - stop. Your vocal chords are an incredible but sometimes quite delicate instrument. Take care of them. Technique really matters with singing, even more than other instruments.