How can I get custody of my one year old child?

You will have to file a case for child custody in the concerned court of the place in whose jurisdiction your residence is located or your wife's residence. You can prepare your ground which are favourig you for the child's betterment and custody but try to focus on solid grounds as the child is very small and young and most of the times where the child is toddler the court favours the mother.

Dear Sir,
As per law custody of a minor who has not completed the age of five years shall ordinarily be with the mother.
However we can move an interim application of custody as the court see the welfare of the child inorder to secure the paramount interest of the child. You are required to give cogent reasons that are indicative of and presage the likelihood of the welfare and interest of the child being undermined or jeopardized if the custody is retained by the mother.