I would step back from bash and terminal if the primary goal is learning swift. You don't need to get to the repl in terminal and I would argue - if you have an iPad, you should start there instead of Xcode.
If you want to (or have to) start on the Mac - open Xcode from the App Store and then make a new playground - save it to your desktop and you should have a window that looks like this to start coding without needing bash or the more detailed setup page you linked to.
The help for playgrounds should get you going - it's much easier to open the help in the app, but it's also available on the web.
There's a time to learn bash and terminal and maybe that's your end goal, but reading your post I'd rather point you to the applications designed to remove all the plumbing, patching, command line configuration and get you playing with the actual code and learning swift.