Re: iCloud sync didn't work when if first got my iPhone 6, how do I do it now?
If the photos were in your photo stream and are less than 30 days old, then configure your iPhone 6 with iCloud, and then enable photostream. The pics should sync to it. If the photos were in your camera roll when you made a backup up of your old iPhone, then restoring that particular backup should restore the pics onto your new iPhone 6. Depending on how many pics you have, it may take some time. Make sure you're connected to Wi-Fi to speed up the process a bit.