SQL Server has some helpful built in reports to give you statistics about objects, indexes, and users and more. The best part about this feature in SQL Server is that its included without having to buy anything else. I will give you an overview and show you how to access/run the reports. In part 2 i will drill a little more into a specific report that can be used to find Schema Changes
There are some 3rd party diagnostics type tools out there that will provide a lot more detail and historical information that the Reports tool. But since you already own the tool, you can use it as a starting point for some diagnostics analysis.

To access the reporting tool, log into SQL Server Management Studio using a system administrator type account, like sa.(Though You could use any login that has access to the database that you will be running your report against.)

Expand the Databases folder, and right click on the Sage 500 application database. Select Reports, and Standard Reports and you will see a list that includes Disk Usage, Disk Usage by Top Tables, All Transactions, Object Execution Statistics, User Statistics.

For the advanced students, you can add a Performance Dashboard report. The output displays a lot of information about your SQL Servers counters and some "at a glance" type information.

To add this report, you will need to Google search and find a Microsoft download link for Performance Dashboard reports, specific to your version of SQL Server. For example, here is a link for SQL Server 2012. Just follow the instructions to download it .  Then from SQL Server Management Studio, right click the Sage 500 database, select  Reports, Custom Reports and locate the file named performance_dashboard_main.rdl, and select that report definition file, click Open. That's it you are done. Now just go back to the Reports area, and select it to run it. (*Note that the download instructions may include a script you will need to run against your SQL Server first before you can run the Performance DashBoard report.