If you would like to print an address on an envelope using your WordPad word processing program, you must know a few important bits of information to succeed. WordPad is Microsoft's basic word processing program. You should have this program if you have a computer with other Microsoft programs on it.
Open a new WordPad document. Click the "Start" button on your "Start" menu, followed by "All Programs," "Accessories" and "WordPad."
Determine the measurements of your envelope. A standard No. 10 business-sized envelope is 9.5-by-4.125 inches.
Click "File" on your top toolbar, followed by "Page Setup."
Click "Custom Size" from the "Size" drop-down box. Type "4.125" in the box indicated for the "Left" margin. Keep the right margin at "0." Make sure your top and bottom margin boxes read "1." These measurements position the exact size of your envelope on the screen. Click "Landscape" orientation. Click "OK."
Type your address on the screen. Save your document.
Load your envelope with the flap side facing down horizontally into the printer tray. Hit "Print."