Oksoy: I just wrote a guide explaining this, here you go:

Welcome travelers!

I am sure many of you like myself have failed to find the Witcher 3 forum so instead I decided to put this one here to help any of you who are having trouble activating the free dlc program.

So you have purchased yourself one of the greatest and most anticipated RPGs nowadays.
You downloaded the game and found out the lovely developers of this lovely piece are giving you free DLCs.
Great! Now, to activating them.

First when you look at the game page you will see that there are dlcs on the left. The bottom one is the one you are looking for.
Go ahead and buy it, don't worry no payment required (mine already says owned because I did this step).

Now to activate the dlcs press the 'more' tab next to the play button and go to configure (see attached picture).
After you have entered the configure section go ahead and mark your selected dlcs (see attached picture).

Enjoy your free content and don't forget to drop the developers a nice word.
Have fun and may your hunt be successful.

P.S: Feel free to add me to your friends if you wish to chat or simply talk about how amazing the game is.
-Oksoy

Koemas: Thanks, but that doesn't answer my question. I want to know how to access it ingame.

Oksoy: You can get the Temerian Armor from Bram, the guy you save from the griffin at the start. He will stand at the enter to the village after you go to the inn. The hairstyles are probably in a similar system to that of the Witcher 2.

littlemad: ah! weird... I do not remember that he triggered any conversation about the armor. I guess that I saw a piece of armor but I needed to buy it. is that one? I thought that it was given... even because it required level 4 to use it.

Oksoy: That is exactly the one, no conversation is trigered in regards to the armor.
He also sells horse armor of the same Temerian set that has no level restriction.

littlemad: thx I'll buy it than... but it look very expensive for starting money! :D