Nothing is for free. You need lessons and coaching to get the best from your voice.
Why not join a local choir (doesn’t have to be a church!!) you will get practice and coaching and have a good time as well.

to get over that stage fright go to karaoke locally as often as you can manage, every night if you can. This will give you practice, help you find good songs to learn and build up your confidence and it doesn’t cost a cent!