I am lonely and I don't know what to do

Heyy. I am so lonely and I don't know what to do the thing is I am introvert. I don't know have friends either so I can't even have a relationship.. I am insecure too have low self esteem.. I don't know how or where could I find friends so I can stop being single and find someone. I am female 21 years old a lesbian it's even harder because of that..