The main function in this package is gfan, which computes all of the Groebner bases and initial ideals of a given ideal. A useful feature of this function is that it can handle symmetries in the ideal. If you want the geometric information of this list of Groebner basis, see groebnerFan.
There are other functions in the gfan package. If you wish to use one whose interface is not included here, you have two options: either write the interface yourself, and then send it to the package author, so it can be included for others, or ask the package author to write it.