How to setup domain name email accounts using a webhop domain?

Can I suggest that, given your level of knowledge you've chosen the hardest solution for getting your email running. If you'd gone down the route of getting somebody else to run the mail service you'd be up and running by now. If you're not familiar with running a mail server you're also likely to run into problems with lost email while you get it working.

Also, have you remembered to arrange for MailHop Forward, or a similar service, so you can send email from your mail server without it being rejected?

The hostname you use will be the hostname you've configured in either Custom DNS or Dynamic DNS to be updated by your chosen update client. It will look something like myhost.example.com, if you try to use something like myhost then your mail server won't be reachable (think of it like sending a letter, if you just send it to "Bob Smith" it'll never get there, if you add the full address it will).

Do read and work through this guide for setting up port forwarding so your mail server is accessible from the Internet.

Use MX Toolbox to test your mail server before updating your MX records.

The MX records must contain the full hostname that points to your mail server. That certainly won't be einsvanianmanufacturing, it'll be the hostname that you're updating to point to your mailserver.

Since you're using Custom DNS you're pretty much there (though I note that einsvanian.com isn't registered).

You've got a number of options.

1. Get somebody else to manage your email - DynDNS don't offer this but many others do (including the free Google Apps). Simply follow your mail host's instructions.
2. Host it yourself - simply ensure that your MX records point to your mail servers. That can be a dynamic IP, in which case you'll need something like MailHop Outbound.
3. Redirect your email elsewhere, using MailHop Forward, though whether you'll be able to send using your domain name will depend on where you direct the email to.

If you indicate which is you're preferred option I (or somebody else) can provide more information.

can you give me an example of a hostname to put into MX using Hmailserver?

what do you mean hostname? do you mean HMAILSERVER? what if my mailserver is behind a dynamic ip address?