To begin with we are not sure if she wants to have sex or you think she does. Do keep in mind that engaging in sex with an Aunty may seem fun and casual but can turn into a very difficult situation, such as social embarrassment, unwanted pregnancy, blackmail.
For ideas around sex, check these links. You can try them in English as well.
http://lovematters.in/hi/resource/ways-make-love
http://lovematters.in/hi/resource/making-love
To begin with we are not sure