Make sure there are no white spaces between letters or characters. Make sure you didn't type a letter or character twice, by accident. The person or place that provided the address may also have typed something wrong. Try a more likely spelling. Look in your Preferences menu to turn off this feature.
Some pages end with an .htm extension, others end with .html , and some have no ending at all.
If your link doesn't work, click your cursor at the end of the address in the URL box , change the ending, and click Enter to try another extension. Sometimes Webmasters revise their sites and old links no longer work. Try shortening the address. Go get it, below. Read the books below.