These change every season and there a 4 objectives to complete the challenge. The first is to buy a certain type of car, and the rest are to do a wide range of other tasks. This can include getting 3 stars on a danger sign or getting air skills. For stuff like getting 3 stars on a danger sign, you can search for specific tunes to upgrade your car that the community has made. Many of them are just titled "FORZATHON" or the name of the danger sign.
Sometimes the skill challenges can be tough to do. If you have one requiring you to get triple passes, you can search for this in the community blueprints. There is a good chance someone has made a race where the AI drivers are terrible and getting triple pass skills is super easy. The community is good at making tunes and races to complete these challenges.
Once all 4 objectives are completed, you'll get the achievement.