This question is a little too general. Here is what you usually do. First of all, you have a data set, and then you either want to calculate some characteristic quantities like mean, std, ..., estimate some kind of parameters or you may want to fit a curve to extrapolate further conclusion.
There are quite a few software packages that might help you in this regard, like SSPS, STATA, SAS, .... I think SAS is the king in the category of statistics saftware, and it not only helps you build models but also helps you understand them. Practically, here in the US, I have not heard that someone uses SAS but doesn't have a job.