Need help for a simple skill tree mod!

[LOKKI]

So I am making a mod for a private world that only me and few friends use, and I need to somehow lock out skills based on your character level.

Like you need to be level 100 to gain access to XP multiplier of 200% etc.

 

So I tried this; <level_requirements level="50"><requirement name="PlayerLevel" operation="GTE" value="50" desc_key="reqGenericPoints01"/></level_requirements>

And I just copied it from the inter webs without basically even learning what it refers to :D

 

I just need someone to clarify to me how does this skill req even work.

 

Thanks in advance!