Hi Chris,
The Script Task Name drop-down list populates with scripts you have saved as a Saved Task. To save a script as a Saved Task, select it on the Scripts tab and click Run. The Run Script dialog box appears. On the Run-Time Settings tab, select Run Now and Save as a Task or Save as a Task (depending on whether you want to run it now AND save it as a Saved Task, or just save it as a Saved Task to run later). Continue through all of the tabs in the dialog box and click the Run button. The script is saved as a Saved Task, which allows it to be selected as a Scheduled Task.
For more info, check out the following link:
https://emc.extremenetworks.com/content/oneview/docs/tasks/docs/ov_ht_schedule.htm
Thanks!
John