How to train my 9 months old to drink from a cup? Or is it too early to train ?

9 months might be a little early. Babies that age aren't very coordinated and will likely spill anything in a cup. Maybe try in a few months time. Start off with a sippy cup or a straw first before progressing to a proper cup. https://www.ikea.com/sg/en/p/boerja-training-beaker-00213884/