There is no save button anywhere. All data is stored magically out there on the web. 

Notice at the top edge of where you input the W-2 it says the employer name? Just to the right of it is a plus sign (+), click that and VOILA! a new place to input another W-2. 

Welcome to the club. PTO takes some real getting used to. 

HINTS: Above where it says  General is a search box - very useful

When you Check Return, you can view the forms. If you can't find the input, find the form, then the box or line you want and CLICK on the box or line and VOILA! it takes you to the input (most of the time)

Good Luck