In order to make changes to your Writers Work profile, you will need to make sure that the edit mode is on. To do that, toggle the eye-shaped icon in the upper right-hand corner. When the "Add Portfolio Piece" box is visible, it means that the edit mode is on. 

To save the changes you make to your profile, simply click the icon again to turn off the edit mode. When the "Add Portfolio Piece" box disappears, it means that the edit mode is off.