Kill Switch help and a story for y'all

I bought an 85' rm250 at the beginning of the summer and it has no kill switch. I have been meaning to put one on, but haven't yet... until now. I got to this riding lot with a friend, fired up my bike and was just about to put it in first when the throttle stuck wide open! I started to freeak out a little, so I figured I would put it in 4th or 5th and let the clutch out. Then I pictured myself flying at full throttle in one of those gears if it didn't die, so I stepped off and tried it. Well it through me to the ground in a doughnut and finally died. It was pretty scary. I thought there was no damage, but then norticed that I had completely shattered my bro's brand new 2005 truck's rear window from shooting rocks into it. The repair cost as much as I paid for my bike!! $*#@ ! I know I should have just shut the gas line off, but it happened so fast and was so damn loud I couldn't think. :bang:

So, anyways I bought a kill switch and need help with wiring. There is a connection wire hanging down from my gas tank, that I assume is what I need to connect it to. It is black with a yellow stripe. The other wire is a ground right??? Just want to make sure before I wire something wrong. All the other wires seem to be connected to something already. Thanks in advance. :ride:

So no one evn wants to reply with how stupid I am? :boss:

THANKS Kevin. The throttle would not unstick - next time I will try your alternatve. Now I have a kill though.