In Notepad, you'll have to do this the old fashioned way, with a spelling dictionary. If you're in Notepad, just save it. File names should have no capitals, spaces or punctuation. In the old days, it was a good idea to limit titles to 8 characters, but that's usually not a problem these days. What you have should look like Figure 1.
Tags are easy to spot.
The second with the forward slash is the closing tag and isn't always used. Most people enter their tags in uppercase to make them stand out from the rest of the text. You haven't seen anything yet. Then save this file. It should look like Figure 2.