Selenium Junit将webelement的值写入excel

In Selenium using Junit I am creating a registration into a website. Once the registration is successful a MRN number will be generated . I want to write this MRN number from the website into Excel sheet .Which I will be using for my further test cases . When I am trying to write it I am getting a error as type Mismatch .As the value to be written into the excel is String and I am fetching a webelement .Can one help me and let me know the method to write the value of a webelement into excel sheet . In Selenium using Junit I am creating a registr