The Renderings Browser (Render > Browse Renderings command) shows you all the pictures you have rendered since you launched solidThinking. Once you select a picture (just click it), you have the possibility to save it or delete it. The Renderings Browser also allows you to delete all the listed pictures.
When you click the Save button, a file requester that lets you save and name the rendered image appears.
You can set a maximum number of rendered pictures that will be displayed in the Rendering browser and stored in the /solidThinking/Images folder in the Renderings buffer section of the Preferences panel (to open it, choose the Info > Preferences command).