Just start off slow by fingering and place a hand on her stomach above her va ja jay,
start fingering her faster with more fingers and stimulate the clit while doing that ,then try to reach a soft area inside her va jay jay and massage it with one finger, while you keep fingering her fast. keep doing that until she squirts..
here is a link that you can read, that's how I found out about this! not that I have tried or anything..