This first tab is where you enter information about your item. Dublin Core is a metadata schema, or a structured set of fields that you can use to describe your item. Metadata is “deliberate, structured data” about your item. In Omeka, metadata is broken up into 15 subfields including Title, Creator, Description, Date, and more.
This is where you will consult the style guide that you created (or, perhaps, the one your instructor or project collaborator created) to enter your metadata in a standardized way to make sure your items are discoverable through searching and browsing.
Field name: In the above screenshot, the field name is "Creator."
Description: "An entity primarily responsible for making the resource" is descriptive text intended to help you understand what to enter into this field.
Text box: The text box is where you type the value of this field--in this case, you would enter the creator of your object.
Add Input: You should break up multiple values into different inputs. For example, if you were describing an item with two creators (e.g. a book with two authors), you should enter one name into the first text box and then click Add Input to add a second textbox for the other author's name.
Use the arrows at the bottom of the page to learn more about the next step of creating an item: further describing your item using Item Type Metadata.