Hello,
I was wondering if it is possible to tag photos w/o logging in first, and if so what code needs to be changed to accomplish this.

You can set fields in the "Keywords" IPTC metadata of the image. Zenphoto will import those when it discovers the image.

Hello,
I appreciate the response but I was looking for a way to add tags and descriptions to photos via zenphoto w/o the need for users to log in. We are using the gallery only w/in our school so security is not a big issue.

Sorry, editing gallery data is limited to authorized users. I think you can understand why.