Students have typically worked through tutorials by reading the material, typing helpful notes in their markdown document, and typing the provided R code into “chunks” within their R Markdown document, then running those chunks. (NOTE: it’s better for you to practice typing the code, rather than copying and pasting!)
You can insert as many chunks as you’d like. Chunk insertion is achieved by selecting the green “+” icon at top of the editor panel, and selecting “R”. Or go to the “Code” menu drop down and “Insert Chunk”.
The key advice: keep your work organized by using headings. There’s an option to view your headings all in one navigation pane by clicking on the navigation pane icon at the top right of your editor panel.