Guys do you ask the girl to be yours or do you let her know by actions.. Please help?

If in school - give her your class ring or jacket. If she accepts, she is acknowledging she is yours.

Out of school, you will know by the way she treats you. She will always be available to go out with you.
You can give her jewelry to show your intentions and then watch her response. If she accepts, assume she is yours.

Caveat!
Now children please don't think another person can ever belong to another person. That would be slavery. In this context we refer to belonging as being someone closer than a friend but not ready to be husband and wife.

both ways. but mostly its through actions.
in my story i let my gf obius that i want her as mine.
v guys hold theyr girls close physically on sm times , play silly with em n ofcorse help her pick up dress n seem to listen 2ur stories... deese r our ways by action n ofcorz d final french kiss n sex later wn gettin serious...