How to use classification?

[Archaeojp]

I would like to build a classification model to then do a prediction for unknown samples. I have a set of clay samples and then a set of ceramic samples and would like to see what the predicted clay classification for the ceramic samples would be. I am able to build a model using the clay data, but how then can I apply that model to the ceramic data? In the classification workflow and in the example data, all the record already have a class and the process outputs a prediction of the class.
How can this be used to generate a class prediction for unknown samples?