how to connect

ineed to make a lead, same as what is on a Mouse or Modem The Plugs Are 9 Pin
Can you help me in the wiring up process
As i need to make a serial 9 pin link between two computers
can you send me a drawing of the connections
i believe i only have to connect 3 wires
Ground, Send & Recieve
but what pin numers do i use
Thank You I Will Be Most Obliged If You Can Help