Documentation for JIRA 6.4 EAP. Not using this? See below:
(JIRA 6.3.x documentation | JIRA Cloud documentation | earlier versions of JIRA)

Title: Adding the Activity Stream Gadget  
Author: Rosie Jameson [Atlassian] May 24, 2009
Last Changed by: Ruchi Tandon[Atlassian] Dec 15, 2013
Tiny Link: (useful for email) https://confluence.atlassian.com/x/tYBiCw
Export As: Word  
Hierarchy
Parent Page
    Page: Customizing the Dashboard
Labels
Outgoing Links
JIRA 6.4 EAP (4)     Page: Customizing the Dashboard
    Page: __ActivityStream
    Page: Adding the Activity Stream Gadget
    Page: __gadgets_desktop_config