The immunizations tab is typically part of Meaningful Use and can be toggled on or off under the desktop security tab.  As such, a particular agency may choose not to add immunizations information in OnTarget Clinical.

To add immunization information, click on the +Add button.

Several drop-downs are available.  Drop-downs of particular importance are the "date administered", "time administered", "administrator", "administered amount", and "vaccine name" fields. 

Click on the Update button to update the information or click on Cancel to cancel the edits.  Note:  Update=Enter; Cancel=Escape.