#1. Go to gmail and log in. (I assume you already have a Google account., if not Sign up here)
#2. After logging in, locate the gear icon at the top right corner of the page and click on it.
#3. Select Settings.
#4. Select the General tab, if you are on it.
#5. Scroll and click on "select a picture" under My Picture section
#6. Select My Computer from the left side ( Since you are uploading the picture from your computer)
#7. Click on Choose file
#8. Locate the picture you want to upload from it's folder on your computer.
#9. Click on Open, wait for picture to be uploaded
#10. Click on Save Changes at the bottom of the page and you are done.