Want to add an idea but I have no idea how to find the id.

It follows this format:

[Prefix_]your_idea_name

I'm going to use your mod "Felonian Future".

For the idea list "Stuff related to new felonian focus tree" you have the prefix "FEL"

The idea "Mr. Cole Sniff II" gets converted to "mr_cole_sniff_ii", as the name gets put into lowercase, spaces are replaced with _ and anything which isn't a number/letter (in the English alphabet without diacritics)/underscore is removed.

So the idea ID is: FEL_mr_cole_sniff_ii

Thank you!