I just re-read your post and if you want to use /pex promote username

You need to set the level for each rank. You don't need to specify a ladder (or path) if you only have one path.

So it would look kind of like this

groups:
default:
permissions: ' '
options:
rank: '1000'
Mod:
permissions: ' '
options:
rank: '900'
Admin:
permissions: ' '
options:
rank: '800'
Owner:
permissions: ' '
options:
rank: '1'

InvisibleI have PEX installed and I can't figure out what my groups ladder # is, I type /pex groups and this is what it says.

Default #0 []
Mod #0 [Default]
Admin #0 [Mod]
Owner #0 []

there is other groups but its all the same number... I just want to know how promote my friend to moderator...

If I created Pex it would be as simple as possible example > /promote name rank
not something stupid like /pex promote name ladder --- wtf is a ladder, oh right that thing you climb...

I never even set up ladders.. Just do it like this /pex user <user> group <add/set> <group>

If you have not setup any ladder then you can just do /pex promote username

Most likely it looks like this:

options:
rank: '1000'
rank-ladder: default

However, you need to set a rank to each of your groups. A higher number = lower rank. So Admin is usually 1 since its the highest.