Printing can be done by clicking on the "File" tab at the top left of your Excel window, and selecting "Print" from the side-menu on the next screen that comes up.
The Print Screen provides a preview of what the printed worksheet will look like. It's always useful to look at this before printing, especially since Excel does some things by default that might not always be desirable. A good example of this is that Excel's default page orientation for printing is Portrait, which is usually not ideal. That can be changed to Landscape by clicking on the dropdown menu for orientation (where it says "Portrait Orientation", on the picture above) and changing it to "Landscape Orientation."
There are a few other settings worth noting. If, in the preview, you see that your spreadsheet will print to more than one page, you can adjust the scaling to get everything on one page. The last dropdown box under settings (where it says "No Scaling", on the picture above) has options for shrinking the whole sheet so that it prints to one page, as well as options for just shrinking it vertically or horizontally, if you just need to address either extra rows or columns going off the page. (Note: There is one additional option for helping get your content on a single page, discussed below.)
Another change you might want to make is to set up your spreadsheet to print the gridlines from you datasheet (this will make it much more readable on paper). This can be done by first clicking the blue "Page Setup" link at the bottom of the list of settings, then clicking on the fourth tab at the top, labeled "Sheet", clicking on the check-box circled in the picture, below, and then hitting OK.
One other feature for printing that is useful is that, upon returning to the regular view from the Print Screen, there will now be a broken line visible at the right of the sheet which denotes where the page ends for printing purposes (there are also broken lines running vertically between each page, but these are of less concern). Anything to the right of this line will print to another page. This allows you can make minor adjustments to the widths of your columns and know whether or not everything will fit on the page, before you go to print again.
Once you are happy with how the preview screen looks, hit the "Print" button to send your spreadsheet to the printer.