1) If you are on a "album page", select the photo you want to download by clicking once on the image with your mouse. 

This is what a "album page" looks like on Flickr:

(trick: We have found that Flickr has trouble remembering where your were, 

when you want to go back to the "album / photo set page" from a "photo page". You

can get around this on most web browsers, by using the  right-mouse button

and selecting "open link in new window", instead of the using the left button. 

Once you have downloaded the photo from the new window, you can just close 

the new window and you will be back where you were, on the "album / photo set page".)

        Here is the "new" photo page (large menu on right side of page)

3) Click on the download icon, in the lower right hand corner. It looks like this:

When the menu pops up, select the "view all sizes" option. You should see a page that looks like this:

4) Select "original".  This will start the download and a copy of the photo will be saved on your computer.

5) You can now either print the photos on your printer,  copy the photo(s) to a USB thumb drive and take them to a local store to print, or use a online printing service like Target, Walmart, Snapfish, ... to order prints.

Note: We found this YouTube of someone demonstrating the process on video. You may want to take a look at the short video too, if you are having problems.