I can reduce the size of pages to make multiple of them fit on my screen, but then they are never oriented properly :( Is there a way to actually split my screen as a command on my MacBook Air? I imagine that would line the pages up automatically.
The supported Apple way of using split-screen for El Capitan onwards is documented at https://support.apple.com/en-gb/HT204948 in the section titled 'Use two apps in Split View'. It works nicely for apps that support it. The most up-to-date docs for Mojave are at https://support.apple.com/en-gb/guide/mac-help/use-apps-in-split-view-mchl4fbe2921/mac
You can hold and drag the green maximise button of a window to one side of the screen to 'lock' it in position, then select another window to fill the other side. The same functionality is also available in Mission Control (ctrl-up arrow).
I'm not aware of a command that will do what you require, but it's possible using the GUI gestures.
While as mentioned in the other answer, Split View feature available in OS X El Capitan and later lets you use two apps side-by-side.
However, that approach comes with certain limitations. The apps need to be in full-screen mode, there can be only two apps side-by-side, and both of them share half of the screen each.
You can use a 3rd party app that lets you quickly and easily align app windows. Divvy is one such (paid with free trial) app that lets you easily manage app windows. It lets you configure a keyboard shortcut which gives you control to quickly and precisely set frontmost app window layout.
Divvy is available for download on the Mac App Store:
Free trial can be downloaded from the app homepage:
Note: No affiliation whatsoever with the developer of the app. I find the app useful in my workflow and use it on a regular basis.