Spacing between paragraphs?

Is there a way to add a carriage return, or some kind of spacing between paragraphs?

Yes, to both questions. Of course, to insert a carriage return, just press Return again. But for most things, unless your publisher really wants an empty line between paragraphs or you need it for something like Markdown, you’ll want to use visual spacing instead. That can be set up in the Format Bar by clicking on the line-spacing tool, and selecting “Other…” At the bottom of that panel, you’ll find an option for setting how many points of spacing should be applied after a paragraph.

You’ll probably want to set that up as a default, however. Get things looking right in your editor and leave the cursor blinking in a paragraph you wish to use as default, then visit the main application Preferences and click on the “Formatting” tab. Click the Use Formatting in Current Editor button, and verify that everything looks okay in the preview (you can further tweak the appearance here as well with the formatting tools). Now any new documents you create will automatically take on this style.