Last step is to evaluate and visualise what has been run. This step can be done using multiple different software packages, among which also Gmsh. For this reason, the first couple of tutorials will use it as to not add more complexity than necessary.
Later tutorials will use VisIt, because of its more powerful nature, and the possibility to script its use. You should, however, still be able to use the knowledge of the first tutorials to finish this walk-through using only Gmsh.