If you want to skip the first command-line-based steps, you could start from the read counts using the recount package and their workflow

EDIT: Some background info -- both, Giovanni and me, recommend you dive into comparing the gene expression profiles derived from RNA-seq for multiple samples. That's a classical bioinformatics and R-based analysis called differential gene expression -- you may want to read up on the general details of RNA-seq before you start the analysis so that the results make more sense. Conesa et al., 2016 might be a good starting point.