Depending on how you've written the reports, there are a couple of options. If you've written them in SQL it's significantly easier.
On your SSRS reporting page (http://something/Reports) there's an upload button. Upload your reports to there. Most errors found at this point are to do with the datasource being incorrect (Make sure that: Data Source
= YourCRMSQLServer; Initial Catalog = YourCRMDB (in SQL Server); - Make sure the account that runs the report has necessary run permissions etc.
Then you can use http://something/ReportServer to link people to the report. Is usually found under your organisation name or where you've uploaded the report.
If you've written them in FetchXML, there's a little bit of work you need to do changing the data-source (Same upload process) - Basically 'Manage' your report under the Reports page, set the DataSource to the correct FetchDataSource (YourOrgansiation/CustomReports/FetchDataSource)
and test. You don't want the root data source, you want the ones inside the organisation data source list.
- Missed the XML bit.
- Note: This only applies to ON PREM deployments
