SCCM 2012: use/upgrade to latest version (current branch), how?

Hi,

I have setup a LAB environment with, what I assumed, the latest version of SCCM 2012 SP2

Version Full Version   UI Version Phase ReplicationPhase Estimated Number of Clients Server Platforms User Organization Type
------- ------------   ---------- ----- ---------------- --------------------------- ---------------- ---- ------------ ----
8239    5.00.8239.1000 8239         455                0                           0               32                      1

Now I read that SCCM current branch is newest version and there you can upgrade from within SCCM.

My questions:
1.can I upgrade to current branch from my version, if yes how?
2.if not, what version should I download/use to install SCCM

J.