You can use them raw. For raw prep I usually scrub the outside of the beet and remove the stem and leaves. You can save the leafy greens from the beet and use them in your blast as well. Just remember a little bit of a raw beet goes a long way!
You can also steam them. I usually cut them into chunks and place them in boiling water for 15-20 minutes or until I can I can poke them with a fork and they are soft. After they are boiled the skin can easily be peeled off and they can be stored in the refrigerator for up to 1 week.
You can also buy already prepared beets at Whole Foods and Trader Joe's. Hope this helps and good luck with mastering the all mighty beet!