How do I get "JSESSIONID" to pass that as a parameter in the command.

We have a requirement to integrate IBM forms and RTC and covert the requirements as a RTC work item. IBM form supports REST API and we are planning to use RTC rest/OSLC rest API commands to achieve the same.
 
While we could extract the details from RTC, but when we update / create workitems in RTC, we hit with following error.
 
"errorMessage": "The user has the roles required to perform this operation, but the permission has been denied because this request might have been forged by a malicious website. To prove that this request is not part of a CSRF attack add a new HTTP header with the name 'X-Jazz-CSRF-Prevent' and use the current JSESSIONID value as the value."
 
Help needed: How do I get "JSESSIONID" to pass that as a parameter in the command.
 
Appreciate your help to resolve this issue.