Much like a museum exhibit, Omeka's exhibit feature allows you to highlight your items by organizing them into pages (you can think of pages as the "walls" of your exhibit).
Since the topic of the exhibit needs to be defined before you can add items, you should take time to plan out your exhibit before creating it. Refer to "Omeka Site Planning Tips" link in the "Additional Resources" box at the bottom of this page for advice on how to best plan your exhibit.