If you want to retrieve a font by name, you need to use the findfont operator. You can then specify how big the font should be and make it the current font. For example, let us say that we want to start typesetting in Times Roman, and we want it to be set to 20 points. Your printer will usually come with a set of built in fonts and will almost always allow you to add more. The names of the fonts available will vary from printer to printer, but Times is almost always present.
Fonts typically come in families.
The show operator is used to typeset text on the page. Text can be considered to be part of the path, so you must also have set the current point with call to moveto or an equivalent operator. You can actually try this example .