A guide for this plugin would be nice

[EleosOS]

A video or a wiki that explains things like selection and props and all of that stuff and how all the commands work would help out a lot, I can't figure it out myself.

[bakapear]

I'd need someone else to do that because I'm pretty bad at explaining how things work.
But I can give it a try for selection:

You can select props with the command !fire !aim select (value)
If you put a value in (!fire !aim select 500 for example), it will select all props that are 500 units away from you.
If the value is 0, it will select the prop you are currently looking at.
If you don't give a value at all, you will enter selection mode and then you can select/deselect props using the console command +speed (Better bind it to a key)

Now if you want to do something with the selection you'd do: !fire !select <action> (value)

If you want to color all props red: !fire !select color 255+0+0+255
Move them 100 units upwards: !fire !select addorg 0 0 100
Clear entire selection: !fire !select clear

Thats all I can offer and I hope this somewhat helps you.