Pressing the "Query" button on a list brings up the Query Wizard, an interactive way to select specific items. The Query Wizard begins with a list of your previously saved queries. You can select one of these, or add a new query.
The "new query" process starts by presenting you with a list of fields to choose from. Select the field you wish to use in your query, and press Next.
Select the type of comparison you wish to make, and press Next.
Enter the value that you wish to compare the database field value to in order to "complete the expression". Press Next when you are done.
The query wizard now presents you with the comparison expression you have created. You can now either add to the expression, or press Finish to signal that you are done. Once the Query Wizard is completed the list of items that match your expression will be displayed.