How to interpret interaction effects in a repeated measures ANOVA?

Hi all,

I need your help!
I have conducted a 2x2x2 within-subjects repeated measures ANOVA and have found:
1) main effect factor A significant
2) main effect factor C significant
3) interaction effect A*C significant

I am unsure how to interpret and follow up the interaction effect using SPSS in order to interpret the main effects correctly. What steps can I take? I would immensely appreciate your help :)