[galaxy-user] How to find out SNPs and point mutations in RNA-Seq data using Galaxy?

HI, I am new to the RNA-seq, and the only available sources for me to do analysis is the Galaxy server. I want find out SNP and point mutations in RNA-Seq data using Galaxy (I do not know if anyone using RNA-seq data to find point mutations, because there is whole Genome sequencing for reporting mutations and SNPs). I have been searching in the forum for a step-by-step protocols for doing it, but could not find it. I have one normal sample and two cancer samples, a TopHat produced "accepted Hits.bam" file for each one. I want to find out SNP and point mutations in the cancer samples, so How do I go from here? Can anyone show me how to do it in Galaxy main server? Thanks! Wei