No Juice???

I disconnected the wires, made a 2 jump wires and stuck them to the hot side that comes out of the starter on the little silver box and presto it clicks and I have lights but won't start. I kept clicking it and then tried to start it and it turned over but didn't start. I tried to turn it again and no juice. I went back up clicked the wires and had headlights again etc. but now I can't get it to try to turn again. What is this little silver box as I call it shamefully. Is this my ignition relay or what and any suggestions on fixing this. Thanks for the info so far. I'm on to something I just don't know what?
Adam