Add as many lines as you need. Check all the links to make sure they are appropriate for your site. If they are not, delete them and replace them with others that are appropriate. Check the JewishGen Links area for ideas. If your shtetl is located in Lithuania, you can add direct lookups in the HaMagid, HaMelitz and All Lithuania databases for your shtetl.
Instructions are here for the code that needs to be added.
See the kishinev page for examples of this. There are no real templates for this. You can look at other ShtetLinks sites for ideas and guidance. There are some templates for putting thumbnail photos in tabular format. Please also read the section on scanning for guidelines on resolution, file size, etc.