how can i replace the underliner of my convertible323 ci? on 2000 BMW 323Ci

i need to change the inside underliner of my car this is a convertible 323 ci i would like to do it my self i bought the kite to replace it but i can t find the manual with the explanation,
where can i find a manual explaning how to replace it? Thanks in advance.

Asked by for the 2000 BMW 323Ci