I made emblems of the four Ancients' symbols... but what do you do with emblems after you make them?

You attach them to your vehicle. There should be an option to add emblems to your car in the menu when you select it in the garage. Then it's a matter of positioning it on the vehicle, which takes a little creativity. You can use a max of 4 emblems (convenient?) and you can only position them on one part at a time (eg. You can paste it on the body, cockpit, or boost, but not the entire vehicle).

So, while we're on the subject, what "Ancients" are you referring to?