Your picture will be saved on the desktop as a .png image file, with a name like "Screen Shot 2018-05-08 at 11.14.58" which indicates the date and time the screenshot was taken. You might want to rename it and add ".png" to the end.
You may submit this file as-is to URCourses.
You may also rename it first and then submit to URCourses as required.
To download Xcode on a Mac, click on https://developer.apple.com/xcode/ or go to the mac app store and search for Xcode. Please use the most recent version.
When starting a new project for CS110, choose "Command Line Tool," name your project, then click on "main.cpp" to see your template. Your input and output will occur in the console, in the "debug area" at the bottom of the workspace. If you cannot see the console. Press Command+Shift+C to activate the console.
Here's a video from January 2017 showing where to download Xcode and how to start using it:
And this video shows how to work with Input and Output files:
If your Mac is old, you might need to get an older version of Xcode:
If you want to run Visual Studio on a Mac, you will need to be running Windows. You can run Windows natively on a Mac using boot camp: