as a first step, you'll need to configure your mysql database as a ReportServer datasource. For this go to the administration module and there to datasources and create a new "relational database". There you can configure your database as a datasource for ReportServer. In a next step, go to the Reportmanager and create a report, for example, a dynamic list. This is the easiest concerning configuration. All that is left is to select your datasource and supply a base query, for example,
SELECT * FROM SOME_TABLE
That is it. For further information have a look at the ReportServer manuals. You can also try the ReportServer forum at https://forum.reportserver.net.
Good luck and happy reporting.