Creating new reports
Because a Report is really just a form View, the nice thing is, you don't need to learn anything new! To create and manage your reports, just go to the Edit Form -> Views tab and create new Views containing whatever fields and whatever filters you need. Views let you create any possible combination of your form fields, as well as reduce the results returned so that only those that match a particular criteria show up.
To learn more about Views, take a look at this section of the user documentation.