Usually, that's just adding an Alias to an existing email account. You
should check your ISP's Email/Account maintenance page for help
with email and forwarding.
Assuming that when you say "change my email address," you mean that you are
changing ISPs, you'll have to ask your old ISP. Some ISPs provide this
service, but not all do. Those that do will probably charge you a small
monthly fee to do this.