When you get on your bike for the first time, please follow those steps for the most accurate set-up:
1. Get the O-ring against the shaft.
2. Get on the bike while standing on the pedals (dont bounce around, just get in riding position).
3. Get off the bike.
4. Note where the O-ring is compare to the whole travel. The O-ring has to travel 15 to 30% for optimized SAG. For DH bikes, it has to be 30 to 40%
5. If you need to adjust the air in your suspension, get a shock pump (sold separately): add air if you need the O-ring to travel less or remove air if you have not enough SAG and repeat previous steps until you get the correct SAG.
Here you go, your suspension is now set up correctly