I've been having some trouble figuring out how to add advantage on saving throws against being charmed and how to make immunity to being put to sleep by magic and need some help.

Figured it out

Would you mind sharing how you did it, I'm struggling to find the solution myself.

Thank you

You would use the following Modifier:

Modifier: Advantage->Subtype: Saving Throws->Description/Details: “against charmed”

The not being able to be magically put to sleep has now been moved to the Elf’s Trance trait in the more recent publications, and therefore doesn’t appear in that box on the character sheet anymore for the more recent elves.