Steps to make your spreadsheet print full page in Excel:

1. Open your Excel spreadsheet and go to the "Page Layout" tab at the top of the screen.
2. Click on the "Size" button in the "Page Setup" section of the ribbon.
3. From the drop-down menu, select "More Paper Sizes".
4. In the "Page Setup" dialog box, select the "Paper" tab.
5. Under "Paper Size", select "Custom Size".
6. In the "Custom Paper Size" dialog box, enter the dimensions of the paper you want to print on. For example, if you want to print on standard 8.5 x 11 inch paper, enter 8.5 for the width and 11 for the height.
7. Click "OK" to close the dialog boxes and apply the new paper size to your spreadsheet.
8. Go back to the "Page Layout" tab and click on the "Print Area" button in the "Page Setup" section.
9. Select "Set Print Area" from the drop-down menu.
10. Your spreadsheet should now be set to print full page. To test it, go to the "File" tab and select "Print". Make sure the "Print Preview" shows your spreadsheet filling the entire page.

That's it! Your Excel spreadsheet should now print full page.