Here is a simple method to add a border in google docs:

Step 1. First, go to Google Docs and open the blank page.

Step 2. Next, go to the toolbar available at the top of the page and click on the Insert option. As shown in the image below:

Step 3. Now select the Table option from the drop-down menu. Check the image below:

Step 4. From the available options here you have to choose just a 1*1 tabletop border to add in google docs. The table will look like this:

Step 5. Now, you have to simply stretch the borders of the table until it reaches the size of your Docs page.

Additional info: If you want to change the thickness, colour or style of the image, right-click on table and select Table Properties option from the menu box. From there you can modify your border as you require. Check the image below:

Step 6. After choosing your desired colour or size of the border click the OK button and your changes will be saved.

Step 7. That’s it you have put a border in google docs!