Can you tell me how to wean my one year old?

Introduce a cup or: a bottle with whole milk instead of a breast-feed. You can gradually drop one breastfeeding every couple of days. Your milk supply should diminish as he/she is taking less. If you haven't done a bottle, you might consider weaning straight to a cup of whole milk and do as I said with dropping the feeds gradually (mostly for your comfort). You can also discuss with his/her doctor.