I Ain't Afraid Of No Ghost!
Choose a ghost, download and beat it!

Go to Dirt Tour, pick a location, and select Time Trial at the bottom where the throwdowns usually appear. Next, pick a track, then a Time Trial Ghosts screen will appear, showing your personal best (if you have one) and the World Record. Select Empty Slot and Leaderboard, and scroll all the way down to the bottom, where you will find the time in 20,000th place. Select this and if it looks beatable, then click Select Ghost. Now click continue. The game will download the ghosts, and you will race against them. You probably wont beat the world record (well done if you do!), all you need to do is beat the time set by the guy in 20,000th place. If this time is too good repeat the process to find a ridiculously easy ghost, they are still out there.