First make sure that your computer or laptop is on and you will have to open your internet browser and enter the following alternative options to access Webmail Login page:
If your website is less than 12 hours old or else is not set properly, enter: http://yourIP:2096
If you've setup the site, use http:/www.yoursite.com:2096
And hit enter.
A new page will open which will require your webmail login details. You will probably find your webmail login details in an email that was sent to you by your hosting company when you paid for their services. Be sure to check your inbox for this email. If you do not have your login information available then you will have to contact your hosting company and prove your identity to them. Once they are satisfied they will send you your login details in an email. Be sure to write or copy this information down for future reference.
Next in the username field you will have to enter your email address; make sure your enter the complete email address, i.e. firstname.lastname@example.org. Then enter Password and hit login. Your password will have been given to you by the hosting company. As mentioned early check your email that was sent to you by your hosting company for all of these login and password information.
A new page will open with options to check mail using any of the listed interfaces, i.e. Horde, Squirrel Mail etc. Select any one of them and proceed. Remember it is up to you which interface that you prefer.
Other than directly accessing webmail, you can alternatively access it from cPanel too. First access cPanel, and look for 'Mail', under the Mail head look for 'Webmail', click on it and you will be on Step 4 from where you can directly check and send mails!
If you have any issues than you can always go online and you will find many different websites and forums that deal with these types of questions and issues. Be sure to check all the forums as somebody has probably experienced the same problems as you and they will definitely have a solution for you.