please explain the process of fertilization in a more detailed and elaborate way

 in general terms:

Fertilization is the fusion of haploid gametes, egg and sperm, to form the diploid zygote. Note though there can be subtle differences in the fertilization process which occurs naturally within the body or through reproductive technologies outside the body, the overall product in both cases is a diplod zygote.....

anyhow fertiliation in diferent organisms has difeerences...