Where can I find the photos autosynced by Google? My Android phone autosyncs all the photos I took to my Google account. Where could I find it? I'm using Google cloud services to sync photos.

I tried looking at my Google Drive, but it says that I don't have any back-up files. I also checked in Google+, but there are no photos.
You should be able to find them here. If they are not there then your phone is probably not actually uploading them.

If it's not uploading photos check that in Settings > Accounts > Google > "your account" > Google Photos is checked. Also check in Google+ > Settings > Auto-backup that it is configured to upload, there are also some settings to control when (on wifi/charging etc).