If you're new to soaping, even MP, don't fret too much about labeling right now. I didn't start properly labeling until I started selling. If someone I gifted a bar to asked for ingredients, I'd just tell 'em.
But to answer your question broadly... if it's in the soap, put it on your label. If you're using a soap base, use the ingredients list provided by the supplier plus any additional fragrance/colorant you add.
For example the BB Goat Milk MP is:
- Coconut Oil, Palm Oil, Safflower Oil, Glycerin, Goat Milk, Water, Sodium Hydroxide, Sorbitol, Propylene Glycol, Sorbitan Oleate, Oat Protein, Titanium Dioxide
You'd put all of that on the label.
I have seen people put "Goats Milk Soap Base" or something similar to that, but I personally don't like that. Especially knowing that some MP bases are detergent free and some MP bases have detergents in them. It's better to be honest so customers can make a conscious decision.