I managed to add it onto this question but how do i add it to an already posted question??

If the photo is on your computer, drag it to your desktop. Then click on the camera icon below. A menu from your computer should come up. click on "desktop" so the menu shows items on your desktop. Find the picture on the menu and click on it and click choose.

If you want to give an example from the Houzz photos, use the Houzz photo icon and click on Houzz url and paste the url from the picture in the box under the Houzz box.

Ok thankyou, still cant do it, not very good at technical things lol