There are a couple of things you could do but the first thing to try is to reset your print area. To do that go to the Page Layout tab, in the Page Setup section click the little black arrow beside Print Area and select "Clear Print Area". Now go to the spreadsheet and select your entire work area, go back to Print Area and select "Set Print Area". Do a print preview and see if that helps.
If it isn't the print area then change the orientation from portrait to landscape. If you don't want the printout landscape then don't try this one.
You can also use the scaling feature. The easiest is to use the scaling feature on the print page. There are a list of options on the lift side of the page. The scaling option is the last one on the list. Click the little black down arrow and select either the "Fit Sheet on One Page" or "Fit All Columns on One Page".
One of those should work, if not post here again or send me an email.