Open Google Docs and create or open a document
Place the cursor where you want the checklist
Click the checklist icon in the toolbar
If you do not see it, click the More toolbar options menu and select Checklist
Type your first checklist item
Press Enter to add the next checklist item
Repeat for each item
Click a checkbox to mark an item complete
To convert existing text into a checklist, select the text and click the checklist icon
To remove the checklist format, select the items and click the checklist icon again