You can write Markdown by hand, but you don't have to. The formatting bar at the bottom of the editor does it for you. Select some text, or put the cursor where you want to add something, and click:
- Text: bold, italic, strikethrough, highlight, and inline code
- Heading: click again to cycle through H1, H2, and H3
- Lists: bulleted, numbered, and tasks with checkboxes
- Blocks: quote, code block, and divider
- Links: a link to another note, or a web link
- Table: insert a table and add or remove rows and columns
To hide or show the bar, run "Toggle formatting bar" from the command palette. Whether it's shown is remembered per device.