Some people might want to see it on YouTube to have it easier but personally I think that a small text should be enough for the most people.
Also... there are enough tutorials on YouTube already.

1. Download the Spino & Compy - Mod from MY Mega-database so you don't need to worry about any type of a virus at all. If you don't trust me you might as well just scan it after downloading. I promise it WON'T break your computer (otherwise I'd risk my server's reputation :P). ----> HERE[mega.co.nz] (262.9 MB)
   
2. Open the game directory by clicking with the right mouse button at Primal Carnage in your Steam-Library.
   
3. Go into the "Cooked PC"-folder which is in the "Primal CarnageGame"-folder (...\Steam\SteamApps\common\primal_carnage\PrimalCarnageGame\CookedPC)
   
4. Put/cut/copy the Mod-file into the "CookedPC"-folder and overwrite the old file.
   
5. >>>INSTALLED!<<<

How to use the mod?
To play as the Spino(saurus Aegyptiacus): Spawn as the red/standard T-Rex
To play as the Compy (Compsognathus): Spawn as the standard brown (Veloci-)raptor

NOTE: The mod is not being supported by the most servers, so don't worry if the game tells you instead "This class is not allowed on this server!".

----> Have fun and I hope this guide helped you! :D