Help, My 6 month old loves her fruit that i ma...

Help, My 6 month old loves her fruit that i make for her. She's only had apples, pears & Banana. Today i thought i'd try introducing her to vegetables so i made her potato. This is how i did it: boiled potato, put in blender with 80ml of formula. can someone tell me if i did wrong and where? should i have mashed? (i'm worried about lumps) my mother in law told me she use to add a bit of butter. I think she might be a bit too young for butter yet.