then i use any commands such as:
/pet help
/pet list
/pet menu
It says use help it is an unknown command

Paste your startup log in https://gist.github.com

-a mod had to edit this because i can't listen to simple directions-

it says :
3:36:51 PM [WARNING] Skipping loading of EchoPet as it does not work with Spigot 1.8 builds!
What version can/should i use

Please read the announcement on the BukkitDev page which explains exactly why this is happening:

If EchoPet is not loading on your Spigot 1.8 build and your server is outputting "Skipping loading of EchoPet as it does not work with Spigot 1.8 builds!", please try running a later Spigot patch. I can't do anything about older Spigot releases blacklisting the plugin (preventing it from loading).

This is not something I can fix, as certain builds of Spigot prevent EchoPet from loading.