Take your time as you don't want to go too quickly; instead take baby time as she might get a bit confuse at first. Try different things; watch what your fingers feel and go with them. After she's had enough of foreplay once or twice insert your finger and keep it moving and rubbing up and down her vaginal walls. This should start to get her aroused a bit as you increase the pressure; don't be afraid to change things every now and then. You can even try flicking her clitoris with the tip of your finger if that stimulates her G-spot too..