Question: I'm building a mansion to impress my friends. 

I've seen pictures of armor stands with ARMS. I searched how to summon one but all of them were either 1.9 or beta. (?how?)

What command do i use to summon one that works?

Answer: 
You can watch [this tutorial](https://www.youtube.com/watch?v=LoLRLKyswTI) (by Sethbling) to see how to show arms and more

But if you want to show arms, try: `/summon ArmorStand ~ ~ ~ {ShowArms:1}`

If you already spawned a ArmorStand and want to add arms (show arms), you can do: `/entitydata @e[r=2,type=ArmorStand] {ShowArms:1}` (tested).
ArmorStands with the `ShowArms:1b` tag will have arms:

```
/summon ArmorStand ~ ~ ~ {ShowArms:1b}

```

You could also set this tag on the closest already-placed ArmorStands like so:

```
/entitydata @e[type=ArmorStand,c=1] {ShowArms:1b}

```