electrical problem

I dont know much about the electrical system so bear with me.
When i go to start my car, what ever it is that the positive battery cable goes to, possibly the selinoid, smokes and it wont start. I tryed to jumpstart it, and it still didn't work.

Whats that part called, why is it doing that, and what do i need to do?

That would be the starter relay/solenoid, but make sure you tell the parts guys its the firewall relay.