First, please remember that you are responsible for checking copyright.

 It is best to format your image before uploading it to the site.  Try to make it reasonably sized, say, 200-600 pixels.

Create a page in the appropriate spot and give it a title.  Then click on the "save" box.  You must then reopen your page, and click on "edit" in the vertical bar on your left.  In the list that unrolls, click "edit" a second time.  This will open your page and give you a window in "rich text" in which to write and upload your image.  On the menu bar in this window, click on the little square with a mountain on it.  A pop-up window called "Image Properties" will open.  Click on "browse" and find the image on your computer, and click on attach.  When the attachment appears, click on it and then say "OK."  Save your page.