photos

open google photoes app -> settings -> backup and sync
turn on backup and sync , select account to backup
below that , select device folders you want to upload to google photoes, quality of photo (select high quality for unlimited storage or you can upload 15GB original quality photo)

below turn on backup on mobile network or the photoes will upload only on wifi network...

Done !
all the photoes will be uploaded to google photoes and you can view it in gooogle photoes app...
after uploading you can delete it from samsung gallery or myfiles , the photo will be on google photos...

note : if you delete a photo from google photos, it will be deleted from your gallery also...