how will i know if my iphone is connected to my computer?

If you have a Mac with Mac OS version lower than Catalina or Windows 7 or later, open iTunes. Your iPhone will appear as an icon near the top of the iTunes window.

If you have a Mac with Catalina or later open Finder and you should see in under Locations in the sidebar. If you don’t see it go to Finder Preferences, Sidebar and check all of the boxes.

On a PC it will show up initially as "iPhone" in Windows Explorer where you see other external devices like USB flash drives or external drives. It should also show up as an iPhone icon in iTunes for Windows.

Also on a Mac one can check under USB in System Report to see if an iPhone is connected. Sometimes it does it without mounting though.