Download & install it from: Mac
During the first-run, bind Gyazo-box with your Dropbox account
https://www.dropbox.com/s/sksons7ug41l2ou/2d39425b-d9df-4a07-ae61-dacae7de82e5.png
The grabbed pictures is in your Dropbox's Apps/Gyazo-box folder. You can manage them manually.
Enjoy it !
Based on the great work of Gyazo and Dropbox-Uploader