To generate a report, select the filters you want to apply and select Generate report. The available filters depend on the report. The report is shown below the filters.
Reports are saved in the background for 60 minutes. This means that when you generate the same report again with the same filter options, it will run faster because it only needs to check if the cached data is still valid.
Note that sometimes report generation may take too long and you may receive a 'Timeout' error. In this case, try running the report again at another time or reduce the amount of data included (for example, shorten the time range).