Gpg4win 2.2.1 button can not find in Outlook 2013

OS:Microsoft windows 7 sp1 x 64
Outlook :2013,pro plus sp1 x 64
Gpg4win:2.2.1

when i installed Gpg4win,then run outlook 2013,I can not find Gpg4win button in Outlook 2013.
How to solve this question?