Most test cases are created as a result of recording a test case. However, in some instances, one, several requests, or entire test cases can't be recorded and must be created manually. This is especially helpful for performance testing of a restful API. For these cases you can use the Request Composer.
To open the Request Composer, right click on the Sessions Grid and select the Request Composer option.
The Request Composer should open in a new tab.
To create a new HTTP(S) request, you can either complete the builder form or click the Raw tab and enter the request content manually.
Then press Send to issue the request and add a session to the bottom of the session grid. After that you can add it to the test case as described in Adding section here.
Request Builder is only available in the Standalone version of StresStimulus. If you are using StresStimulus from Fiddler-Addon, use Fiddler's Composer feature to create requests.