1. You should learn about the Weil Conjectures (which are theorems) 
            for smooth varieties over finite fields, e.g.,
            the Galois representations, the determination of the zeta-function. 
            See Weil Conjectures in wikipedia for a start.
          2. Basics on modular forms (classical modular forms, quasimodular 
            forms, Hilbert, Siegel modular forms)
            The book by Zagier et al. the 1-2-3 of modular forms.
          3. Modularity theorems for some Calabi-Yau varieties over Q or number 
            fields
            The book by Ch. Meyer FIM 22 would be a good start.
          What we want to work on during the summer is to understand how to 
            compute the zeta-functions and more generally L-series for families 
            of
            Calabi-Yau varieties, starting with one or more parameter families 
            of hypersurfaces. For instance, some work has been done already for 
            the Dwork families, i.e., one-parameter family of quartic K3 surfaces, 
            one-parameter family of quintic CY threefolds, and D. Wan's work on 
            arithmetic mirror symmetry.
          Our hope is to try with two-or-three parameter families of Calabi-Yau 
            threefolds.
          Here are some of the articles you should read before your arrival 
            at the Fields Institute. You should try to make yourself familiar 
            with the articles with *. 
          Yui, N. 
            *Update on the modularity of Calabi-Yau varieties with appendix by 
            H. Verrill, in FIC 38
          Yui, N. et al. 
            Arithmetic and Geometry of K3 surfaces and Calabi-Yau threefolds, 
            FIC 64
          Yui, N. 
            Modularity of Calabi-Yau varieties: 2011 and beyond in FIC 67. 
          Lee, Edward
            *Update on modular non-rigid Calabi-Yau threefolds, in FIC 54
          Goto, Y, Kloosterman, R., and Yui, N.
            *Zeta-functions of certain K3-fibered Calabi-Yau threefolds
            Internat. J. Math. 22, no-.1 2011.
          Garbagnati, A., and van Geemen, B. 
            *The Picard-Fuchs equations of a family of Calabi-Yau threefolds without 
            maximal unipotent monodromy, Int. Math. Res. Notes 16, 3134-3143 (2010).
          Garbagnati, A. 
            *New families of Calabi-Yau threefolds without maximal unipotent monodromy, 
            Manuscr. Math. 140, 273-294 (2013). 
          D. Wan
            *Mirror symmetry for zeta functions, in Mirror Symmetry V Moment zeta-function 
            Arithmetic mirror symmetry
          P. Candels et al.
            *Zeta-function of quintic Calabi-Yau threefolds
          S. Kadir
            *Arithmetic of mirror symmetry for two-parameter family of Calabi-Yau 
            manifolds, in Mirror Symmetry V