How may you legally change your last name?

If I do go through with this ill do it when im 18, so a couple of years away. But how can I legally change my last name? I have reasons to want to change it. But im guessing court is involved and paper work? If anyone can find anything on this, could you please post it or a link? Thanks! :)

Let me google that for you

:'( SKY HACKED MY PUTER!!! ITS MOVING ON ITS OWN! Thanks, Sky! :) Im in the US too.