Why doesn't my guitar sound normal? What am I doing wrong?

When I play my different chords on my guitar, the note is supposed to ring. Mine doesn't. I don't know if I am pressing to lightly or too softly on the strings, but I'm almost positive I'm not doing it right. It just sounds like the guitar string is dampened, it doesn't ring like other guitars. I have looked on YouTube to find guitar videos, and none of them have seemed to help me.