Indeed I am now trying to read a series of papers  written by Einsiedler, Lindenstrauss, Michel and Venkatesh that study distribution of periodic torus orbits on homogeneous spaces. They make heavy use of automorphic L-functions, and Eisenstein series on adelic homogeneous spaces, but I almost know nothing about that.
  And it seems that many books on automorphic forms are quite involved and have too many pages for me. So I want to ask whether there are some concise books that contain things about automorphic L-functions, Eisenstein series on adelic homogeneous spaces. 
  Thanks for your attention.