I really want to learn how to sing?

I have never had any lessons but i have playing guitar for 2 years so i have some sort of foundation with music. Ive always sung while playing guitar cause i really do enjoy it but recently i actually started to record my self but i just have a horrible voice. I cant stay on pitch at all and my voice is just really shaky. I would really appreciate if someone could at least give me some tips on how to start to sing or get a basis for my voice. People say to practice everyday and i do sing my heart out every single day but it really doesn't matter if i don't know what i'm doing so i would like it if you could also include some tips on how to practice. Thanks :)