There's at least 2 different styles of footwell lights.
On mine, the white covers just pop off. I have wedge bulbs but some TJs have screw-ins.
If you have wedge bulbs, the LEDs are polarity specific. ie they will only work one way.
So if they don't work, pull them out and turn them around.
I got these ones in green
Search Results For "921-x12" | LED Products | Super Bright LEDs
But check your bulbs - you may need a different style.