Question

how to incorporate literary criticism into essay

Answer 1

MLA formatting is a great reference for incorporating quotations.
http://www.amersol.edu.pe/hs/english/howtohandlequotes.asp
is a good reference.

do no say "[critic] says" instead form the quote as a seamless statement, while saving the ownership at the end of the quote.

Caufield is a flawed character "when he does this-this-this" (critics name) then carry on as if there was zero interruption.

a full bibliography is saved for after the paper this complete.