can't open a link in a web page, goes immediately to down load and then when opened it shows downloaded to windows photo viewer, which won't open

I open a web page, in the web page there is a link to open another link. I click on this link and the doc is 'downloaded' automatically , I click on the 'green arrow' download button at top of screen, the page opens and says 'windows photo viewer can't open the picture because photo viewer doesn't support this file format or you don't have the latest update to photo viewer'!! I just want to open the link. Grateful for advice.