1. Log into your gmail account and go to settings for add Web mail with Gmail.
2. Go to Accounts and Import, go to Check email from other accounts and click on Add an email account for connect Web mail with gmail.
3. In the pop-up window enter your webmail and next for connect Web mail with gmail.
4. Click next again.
5. Enter your full web mail in username and its password, select port 995, check the two boxes and click on add account.
Now you will find all the upcoming mails of your webmail in your gmail. Now if you want to send email of your webmail from your gmail click next.
6. Enter the name that will be shown to the receiver of the mail, check the box and click on next step.
7. Enter your web mail and password again, select port 465 for ssl or 25 for tls, check the box accourdinng to the port and click add account.
A confirmation mail will be sent to your web mail.
Now go to the mail and you will get a confirmation number. Copy the number, paste it in the box and click verify.
You can also check How to login Business Email