Hi,
Your site (spannocchiawritersworkshop.com) is hosted at WordPress.com, and you can see that your domain is mapped in Store -> Domains.
We don't allow plugins on WordPress.com for security reasons. Plugins are a feature only available for self-hosted blogs provided through WordPress.org.
For more information on the differences between WordPress.com and WordPress.org, you can see this support page:
http://en.support.wordpress.com/com-vs-org/
I do want to let you know that you can upload images to a post or page, then you can insert an image gallery with the Insert Gallery button after you've uploaded a series of images in a post or page:
http://en.support.wordpress.com/images/gallery/#adding-a-gallery
I hope this helps! Let me know if you have any other questions.