Compile all of the textbook's terms you need to define. Usually, the words to be in the glossary will be highlighted or boldfaced in the text so the reader will know which words are in the glossary.
List each term in bold type and write its definition after it. You can place the definition underneath the term as a new paragraph or after an "n" dash in the same line.
Separate the glossary into sections. If you have a long list of terms, create separate headings for each letter of the alphabet and organize the terms by their first letter. Although the terms will already be in alphabetical order, this will help readers find a specific term more easily.
Insert the glossary in the back of the textbook.