FYI ~ I use Flickr, but do not use them for hosting my website and blog images. I prefer Photobucket.com for image hosting. People do use them for hosting, so here is how to get an image URL. :) Have a great day!
Click on the Flickr photo you want to use.
Place your mouse over the picture and Right Click
Highlight and Copy (ctrl+C) the file URL
The URL will end with .jpg ~ do not copy the other information at the end of the URL. See what I have highlighted for example.
Paste (ctrl+V) into html
Produces this Flickr Image:
Add width="250" after the .jpg" to size the image ~ change 250 to any number depending on the size you want.