Creating a photo gallery is the same as with most things in Drupal: there are many different ways to reach your goal.
In this tutorial we're going to show you the quickest and easiest way: using the Node Gallery module.
Install Node Gallery
In order to install Node Gallery, we'll need to download and install four different modules:
Upload those module folders to /sites/all/modules/ and then go to Administer >> Site Building >> Modules to enable them.
Create the Photo Gallery
In your Drupal site, click Create Content >> Gallery.
You'll be prompted to set up a node, just as per normal. The only difference is that this node will serve to hold all your photos in a particular gallery. When you've given a name and description for the photo galley, click Save.
You'll now be taken to the finished node. Click on "Upload Images" you'll be prompted to do just that.
Once you've selected the images, click "Submit Images".
When you're finished, the node will look like the screenshot above.
If you click on the photos, you'll see a screenshot like the one below with large versions of the image plus Previous / Next buttons.
Node Gallery will also automatically create a menu link to a list of all the galleries.
Configuring Node Gallery
The sizes and modifications performed on all the images are controlled by the ImageCache module that we uploaded earlier. Go to Administer >> Site Building >> Blocks and you'll see three different options:
ImageCache uses these presets to automatically create the cover images, main display images and the thumbnails. If you click on "Edit" you can change the size of all these defaults.
More settings are also available from Site Configuration >> Node Gallery