SORRY FOR THIS DOUBLE POST!:
Here you go mate... hope this helps:
Step 1: Click Car Showroom2
Step 2: Click My Garage
Step 3: Click on Browse and Add your file
Step 4: Select the type of car you are uploading
Step 5: Enter a description (IF YOU WANT) and then click SUBMIT
NOW, WAIT 24 HOURS AND CHECK YOUR GARAGE!