You can adjust the height of the saddle. These are the instructions on how to do it:

Loosen the nut on the seat post bolt on the bicycle using a 13mm wrench to allow the seat post (with saddle attached) to slide into place inside the seat tube (this bolt also fixes the rear carrier rack to the frame of the bicycle). Align the nose of the saddle with the top tube of the bicycle, and make sure the height of the saddle is approximately where you need it to be to comfortably ride the bicycle. Tighten the saddle clamp in place until the saddle cannot be moved up or down with vertical pressure applied to the nose. Holding the saddle in one hand (typically your left hand), tighten the seat post bolt’s nut using a 13mm wrench. Check that the saddle is still aligned properly. Continue tightening the nut on the seat post bolt until the seat post does not rotate when pressure is applied to the side of the saddle.
And if you don't want to do it yourself, you can always go to your local bike shop and ask them to adjust it for you (or if you have a friend that knows how to do it). You just need the wrench they recommend.