Godparents make the same promises on behalf of the child being baptised as parents. Godparents promise to pray for and support the child and to help the parents to bring up the child in the Christian faith. It is an important and responsible role.
You should normally have at least three godparents: two of the same sex as the child and one of the opposite sex. Godparents can be family members or friends. But the most important thing is to choose people who will take an interest in your child’s spiritual welfare and who will pray for you and your child. Godparents must themselves be baptised, and preferably also be confirmed.
For more information see the Church of England’s Guide to Choosing Godparents.
There is also a section on their website A Parent’s Guide to Christenings with lots more information.