Ask her if you can play, if she says no, ask how long it will be until she gets off, if she says when I'm done, say I'll ask in 30 minutes, if she persists, tell her that you would like to play blockland, minecraft, ECT. Then if she says no, ask your parents if you can play on the computer, if they tell you wait until your sister is done, become impatient with her, do not resort to being physical, because punching a little girl makes you look like a douche.