I often use Instagram to add effect and frame to my photos.
Then, there is a folder named instagram appearing in Gallery; but that folder won't be synced with my Google account i.e. on another Android device signed in with the same account, I don't see that folder.
So my question is that how I can have it synced?
The gallery is showing the Instagram folder cause it scans the whole device and external storages and grab all folders with images. You can't sync that folder but can share once in a while with Picasa so that process will upload images on that folder to Picasa. And then Picasa will sync that folder to your rest of the devices.
Alternatively, you might want to take a look at apps like e.g. FolderSync:
FolderSync is a application that enables simple sync to cloud based storage to and from local folders on the device memory card. It currently support multiple SkyDrive, Dropbox, SugarSync, Ubuntu One, Box.net, LiveDrive, HiDrive, Google Docs, NetDocuments, Amazon S3, FTP, FTPS, SFTP, WebDAV or windows share (Samba/CIFS) accounts, and support for more platforms are planned.
With this app you can define which folders shall be synced where, thus adapting everything to your very convenience.
(click images to enlarge; source: Google Play)
PhotoSync (Sync to Picasa) might be your choice:
PhotoSync is tool for sync photos to Picasa(Google Photos). though limited, you can sync videos too.You can also sync photos among multi devices via Picasa.
