I'm new, and lost. MAME on Laptop with J-pac?

[tridentphotography]

I am trying to convert the Arcade Legends 2 into a MAME machine by adding a laptop and a J-pac, & i guess I need an i-pac too for the roller ball. I am so confused though as to how I get the laptop to work with the existing arcade controls and monitor.
I could certainly use a hand.
I cant seem to figure out where to connect the computer to the j-pac, or how.
also I think the monitor signal is wrong. I got some way out of sync image only, so I will look into a download of some kind of software to soften the vga output to 15KHz. I seem to recall seing that somewhere in a thread. (feel free to link here though if you know what I am talking about)
what plugs into the J-pac? there are 2 of the round connector plugs like a keyboard uses, so if one is for a keyboard, what goes in the other one? and then where does it connect to the laptop? Do I need a desktop?

Please have mercy on me, all help is so appreciated.