All the Parameters from the WorkspaceExplorer Parameters subtree shown as a circle are "plotable". Drag the desired parameter[s] and drop onto left panel at the PlotManager form. Note that parameter names appeared in the Plot form could slightly differ from those of the Workspace Explorer tree.
Select Time interval you are interested in and click Plot button. Note that you may always find out valid parameter time range as well as sampling time: just consult tooltip displayed when your mouse is over the corresponding dataset node of the WorkspaceExplorer tree.
Plot form proposes two choices for time selection either by one time interval (Interval mode) or by a number of intervals (TimeTable or Catalog mode). In the latter case click Time Table or Catalog tab of TimeSelection panel and drag-drop time table[s] or catalog[s] from the WorkspaceExplorer onto time selection area.