Sending email with a new domain name

Hi Folks,

I bought a new domain name for my business. I need to be able to send mail using that domain name. My name is Anne, so I want to send mail from Anne@Mybusiness.com. The folks hosting the site know my work email address because I set it up so if anyone fills out forms on my site, the resulting email will be forwarded to my personal email. I want to be able to reply to these emails from anne@mybusiness.com. How the heck do I do this?

I tried to go to Mail/Add Account/Other Account

but then it asks for a name, email address and password. I tried passwords for my domain provider, my website host, even Apple. Nothing works. Grrrr. AB