First timer. What to do?

Well, I was just too horny I started to look for something that could be used as a vibrator. Turned out I found a body massager that vibrate while it switched on.

I used it with clothes and panties on because I'm too afraid to use it directly on the skin. I put the back of the massager on my clit but I didnt feel anything. Then I tried to move it up and down and then suddenly I think I hit the 'spot' because the good feeling and my body was twitching suddenly. But then I stopped because I dont know what to do and kinda scared.. so what should i do?