After the application of collagen products onto my skin, will it become the collagen of my own skin?

Unfortunately, it will not be the collagen of your skin/dermis.

 The major role for collagen used for skin/hair care products is

basically moisture the skin/epidermis. (As all Finn's skincare

products contains salmon collagen extract, various kinds of 

amino acids and minerals, they moisture and nourish the skin

at the same time. When the skin softened by collagen's moisturizing

effect, the nutrition can be easily taken to the epidermis through 

the pores and it promotes the blood flow and enhances

the metabolism.)