Go to your 'my profile' page.
Click on "General info about myself"
On that page, there will be a line for picture.
Enter the source of the picture into the blank space.
Hit the "Submit" button at the bottom of that section.
That should do the job.
If you are using a wood chipper, you are doing it wrong. Even on this tiny ad:
Gardening and natural building at a delightful pace