Call your local track and ask what tires and compound work best for stadium truck. Get those.

Go to your local track during practice hours / day. Slow is fast, learn how to keep the rubber side down and repeat until you get comfortable keeping pace or anywhere close to pace with the other drivers.

Enter a race, they should have a catch all beginner class that you can run anything in.

Once you have seen the different types of buggies & trucks they are running get the one you like. You will really enjoy a competition level vehicle once you get the hang of driving.

1st and foremost, have fun!