Yea! At long last the photos are appearing! In both the slider and the posts:
http://linuxforartists.com/
Thanks to James and Dude for all their help.
I'll write out the steps for setting the slider photos, for the benefit of anyone else reading this.
Find a photo you like online. Right-click "Save image as" and save it to your desktop. (I won't get into photo rights, but you should only use photos you've taken yourself or photos under a "Creative Commons" license. Always give credit to the photographer.)
Now go to your post.
On the bottom right, you'll find "Feature image." Click on "set featured image." You should automatically be on the "From Computer" tab. Click "select files." Choose the photo you saved to your desktop. Click "OK."
The photo should have uploaded and you'll see it in the window. Scroll down to the bottom and click on "use as featured image." It will take a few seconds to load.
When done, click on "Save all changes." Close that window.
Should take you back to your post. Click on "publish" (it will say "update" if you're revising a post).
Now go to your homepage. The photo should appear in the slider.
Dude or James can correct me if I missed any steps. Hope this helps!
I was wondering, is there a way to edit the size of the featured photo in the post? I like the photos to be thumbnails on the homepage. But in the individual posts, I want the photos to be bigger and with captions. Like if I did a regular "insert photo."
I tried using "Full size pic or video for Lightbox." The only problem is that I end up with two images in the post, which looks weird:
http://linuxforartists.com/photo/how-to-turn-ubuntu-into-a-multimedia-studio/
Can you suggest a solution where there's only one full-sized photo in the post, it appears in the slider, and appears as a thumbnail on the homepage? Sorry for my ignorance.