This is the area where all Worksheets that have been created are listed and where you are able to add a new type of worksheet or duplicate in order to alter an existing worksheet. 

Select the worksheet to view the details.

If you need to edit the file information such as worksheet title, description, if the worksheet is adhoc or published? Press from the list view or from the detailed view then

If you would like to alter the worksheet itself press from the list view or from the detailed view then  to go in to the form builder. 

To add a brand new worksheet press  and follow this article. 

For help on how to build a worksheet visit this article