am i commercial or non-commercial site.

The issue of whether a given site is commercial vs. non-commercial may not be quite this simple. It will depend on how the given rights holder defines those terms.

For example, some hold that any site that attempts to make money is by definition a commercial site. Others rely on whether the attempt to make money is the primary reason for the site's existence. Many personal blogs that stick a few adsense ads up would be considered non-commercial. Still others define "commercial use" as inclusion in a product for sale.

Under the last definition, using an image to create a book cover would be considered commercial use. As would including the image in a collection for sale. Using it to illustrate a blog post, even if the site exists to make money, would not be considered a commercial use.

You have to consider the rights holder's definition and abide by any licensing conditions applied.

As Suzanne points out, though, you still have to honor copyrights. You can't just grab images willy-nilly and use them.