Before you start, Open the Photos app and go through your pictures and videos. Delete anything that you do not want or are duplicates. This will save you a lot of time.
If you have not already done so, download the Google Drive app.
Open Google Drive
Select the “+”in the lower left corner.
Select Upload
Select "Photos and Video"
Select the album with your photos.
Select the photos or videos from your camera roll that you want to be saved to your Google Drive by touching the photo or video.
When you have selected all the photos or videos you want to save, select Upload.
The photo or video will save to your Google Drive.