Accounts allow you to add in details of the organizations so that you can track your leads and deals better.
Edit an Account
Go to the Account tab and select the one you want to edit.
This will take you to the Account detail view. Click on 'Things You Can Do' on the top right corner of the accounts detail. Then select the 'Edit' option.
This will display a window to edit the Account's information. When you are done with the changes, click the 'Save' button.
To learn how to create or delete Accounts, please visit the following tutorials: