A lot of people rely on plug-ins like NextGen to display images on their website, but the built-in WordPress gallery actually works quite well for most situations. Here’s a short video tutorial explaining how to use it. I recommend checking out the codex for deeper explanation of the shortcode and the jQuery Lightbox For Native Galleries if you want a better presentation for clicked images.

Thanks, I learned something! :)
hi, nice tutorial! How did you show thumbnails and main gallery image together on one page and change it without reloading the page?
Is there a feature to turn ‘gallery’ on? The gallery tab is not available to me, just the Media library. I’m using theme twentyeleven version 3.4.1.
The gallery is default on all WordPress installs. You just click “Insert Gallery” from the media uploader in the post.
I kind of figured it out part of it yesterday. It seems like this feature works only in upload form or is tied to the [gallery] shortcode per posting. What i had trouble with was grabbing an existing already uploaded file (like from library) and inserting it into the gallery element on the page or post. In my installation, once i select the gallery item, I see 4 tabs From Computer | From URL | Gallery (5) | Media Library. When i click Media Library to try to grab a previously uploaded photo and put into the gallery, there is no option to ‘insert gallery’ I can only ‘insert post’ Is there another way to get previously uploaded photos into a gallery? Thanks.