Sign in to your account and open the W&I Workbook for the level you want to use. Choose a task that you want to use in your own workbook. Click on the paper symbol in the top right-hand corner, and choose the workbook you want it to appear in in 'My workbooks' from the list you see. The task will appear in your chosen workbook ready for you to start writing or for you to invite others to do.
If you have a subscription to Write & Improve +Class View, you can copy the tasks provided in the W&I workbooks (including +Test Zone workbooks) into your own workbooks and then you will be able to see all your students' writing and feedback and track their progress.