Multiplayer Elite Achievement
Online: reach Rank 22 (Warrant Officer I)
You get points by killing enemies, destroying objectives/capturing flags, helping your teammates out by healing, resupplying them. Pointing out objectives/enemy locations on your map pressing the gets you more points if they get destroyed/killed.
Points needed to reach Rank 22: 405,000
If you would like to know how far you are from your next rank up, use this rank calculator to see how much XP you need.