Haskell simple If-then-else error

I'm really new to Haskell and programming in general. I'm trying to add up the contents of a list without using the sum function from Data.List. Here's what I've got so far:

module Summ
    where
summ :: [Int] -> Int
summ xs = 
  if null xs == False
    then let y = x + (head xs)
         let xs = tail xs
    else print y

I'm pretty sure there's a lot wrong with this code, but for now the latest error is "parse error on input" for the else statement. What's wrong?