Configure domain to redirect

I have a domain on Godaddy:

domain.com

I configured my domain to redirect to

otherdomain.com/~my_name

However, when I type on the browser, e.g.:

domain.com/certificate 

Godaddy redirects to main domain:

otherdomain.com/~my_name

But I would like that Godaddy redirected to:

otherdomain.com/~my_name/certificate

I believe that I need to configure the DNS zone, but I have no idea how to do this (and also I don't know what ask on Google).

Someone one knows how to solve this? Thanks!