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 right hand corner.
Select Upload file
Select 'Photos and Videos'.
Select the album with your photos
If you have mulitple ablums, you need to do this for each one
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
on the Upload to Drive screen, verify the location at the bottom shows 'My Drive', then select 'Upload' in the upper right hand corner
on the bottom of your screen you will see a progress bar.
You will have a green check box once it's completed.