PJ Tierneys guide is spot on! But i made a little video just explaining the whole thing, and just general tips.
Like PJ Said, to be able to get onto Forzathon Live, you have to first qualify for the Horizon Roster which takes around 3-4 in game hours to do.
Remember, you can be as good or as bad as you want, if there are a decent number of people, the 3 achievements can be EASILY obtained.
Its a GROUP effort, so if you want to add just 1 point to the board you can! (Although try not to be that guy lol)
I Explain the ins and outs of the achievements for the first 1.30, so 1.35 and beyond is where you see me doing the 3 rounds and explaining each one.
Thanks for watching, hopefully this helps you guys and gals out!