To first access Disk Utility, navigate to the Applications folder, either by the sidebar in Finder, or by pressing ⌘+Shift+A in Finder. Next, go into the Utilities folder.
In the Utilities folder, launch "Disk Utility".
Upon opening Disk Utility, select "Macintosh HD" from the sidebar and then hit the "First Aid" button at the top of the window.
First Aid will now run on your hard drive and detect any errors. If it encounters any it will present them to you, and you can take a screenshot using ⌘+Shift+4 and then hitting "Space" to capture the window.
And that's it, if your machine isn't showing any errors you're good to go, or if something still seems off more technical steps will need to be taken.
If the guide didn't provide the support you required, or you are still having issues, please contact CDM AV Support at cdmavsupport@depaul.edu or call (312)-362-1297