The “knowing” how to dance thing is not very important for me, as I’ve never had any interest in dancing for dancing’s sake. It’s more the fact that 1) I can’t bring myself to “let loose” as everybody else seems to do, and 2) the fact that I was unable to find a girl who wanted (or at least didn’t mind) dancing with me
Letting loose while dancing is part of knowing how to dance.
Secondly, if you don't know how to dance why do you expect that girls want to dance with you?
For a girl it's not that much fun to dance with a tense guy who can't move to the music. A girl might feel pity for you and dance with you.
If you want that girls dance with you because they think that they will enjoy the dance, you have to learn how to dance.