Types of Omeka:
Appearance: If you would like to change the appearance of your site (colors, design, etc.) you can do so by switching Themes (similar to Wordpress). It’s a little bit trickier, however. In this case, you need to download an Omeka Theme from this list and use the following instructions to upload it to your Omeka directory through Reclaim Hosting: https://community.reclaimhosting.com/t/uploading-plugins-to-omeka/195/2.
Vocabulary: if you get confused about the different parts of Omeka, you can refer to Miriam Posner’s section on Omeka Vocabulary: http://miriamposner.com/blog/wp-content/uploads/2013/03/Up-and-Running-with-Omeka2.pdf