You select File - Graph Response if you wish to graph your simulation data. You may open a browse window to chose the project whose results you wish to plot or select a project from the recently used list.
Once you select a project, a Graph tab is opened with a new plot of the chosen project's response data. For more information on graphing your data, please see Graph tab - Graph tab - Response Viewer.
You may also open a graph by clicking on the Graph Response button in the Sonnet task bar, then selecting "Browse for Project" or selecting a project from the recently used list in the pop-up menu which appears.