Through mixing up and interaction. If you are looking for something then th have to search.
Find a girl who likes stuff that you like.
Find another girl that you like that DOES like you.
Get over it and find a better girl. You can't force your feelings to her.
Ask her
find out if they like you back
Well, to find a good girl you have to ask question like: Do you like good people? To find a bad girl she would be sticking in a bar or dark places.
find another girl that you like completely
Find a way to impress her.
The girl has already chosen your friend. Find a different girl. .
To find ansers
Find out what she likes and then start to hang out with her and she will start to like you ;)
You find a girl and tell her "you like her in a very cute way".