Setting up your printer in Excel can be a bit of a challenge, but with a few simple steps you can get it done in no time. Here's what you need to do:

1. Open Excel and go to File > Print
2. In the Print dialog box, select your printer from the drop-down menu
3. Click on the Properties button (this will open up the printer's properties dialog box)
4. In the properties dialog box, select the Paper tab
5. Under Paper Size, select Custom and enter the dimensions of your paper in the Width and Height fields
6. Click OK to close the printer's properties dialog box
7. Back in the Print dialog box, click on the Options button (this will open up the Page Setup dialog box)
8. In the Page Setup dialog box, go to the Margins tab
9. Under Margins, enter the margins for your document in the Top, Bottom, Left, and Right fields
10. Click OK to close the Page Setup dialog box
11. Click on Print to print your document