To share reference, you have to create an account at Zotero.org
Put your Zotero account's username and password into your Zotero preferences.
You can then create a group library and INVITE the others to join the library. They will need to have Zotero accounts too. Invite them using the email addresse they used to sign up to Zotero.
Save your references into the group library. When you sync to the Zotero server, the reference you added will be uploaded to the Zotero server. Then when the other group members sync, that reference will show up in the group library folder in their Zotero library.
Please check out this great research guide on best practices for group Zotero libraries from Carleton College's Gould Library.
You can create a folder of your own publications in the "My Publications" part of your Zotero library. These will be shared on zotero.org.