Stats help for Research

Hi everyone and thank you in advance for any help you can provide:

I have an experimental design that requires a 3-way (2x3x5) RM ANOVA. 2 Treatments (Pre-Diet and Post-Diet), 3 Timepoints (A,B, and C) and 5 stages within each timepoint (Stage 1,2,3,4, and 5). Can anyone provide a syntax or instructions for how best to set this up in SPSS and if my N=20, suggest any considerable post-hocs? I am currently considering Bonferonni or Tukey. Thank you for your time.