You can choose the park hopper option but I believe you just purchase the Max Pass after you go through the gates.  I did it that way when I went earlier this year and it is very easy.  Just make sure you have the Disneyland app loaded on your phone, an acct created, and a credit or debit card set up on your acct.  Super simple and totally worth the money if you want the pictures and a quick and easy way to get fast passes.  Laserfiche has also offeedr tickets if you plan on going just in the evening so after 4 PM or the last 5 or so hours that the park is open.  It is a cheaper way to go if you only plan on being there may Friday  night after classes only.  Hope this helps.