mixed models in SPSS

[dr_dr_2B]

I am looking to create a linear mixed model for my experimental data in SPSS, but am having trouble inputting the correct variables and models. I have had no previous experience with mixed models and am trying to learn as I go. As briefly as possible, my experimental design is as follows. I am measuring damage to tissues as a function of stress and duration in an animal model. There are a total of 15 animals. I am applying a set of 5 stresses, each at 3 different durations in each animal for a total of 15 samples per animal. I am taking 4 damage measurements per sample, so 60 measurements per animal. I need to know how to input the proper variables into the linear mixed models windows in SPSS to account for the 60 measurements per animal while accounting for stress and duration. Any help with this would be greatly appreciated!