Open up MoleculeSketch. On the upper part, you will find a set of drawing tools. Under the drawing area you will find a settings bar.
Explanation of the toolbar items
Explanation of the bottom settings bar items
The main menubar
Setting preferences
Copy Paste
Saving
Drawing atoms and bonds
Adding ring systems
Adding chains
Editing atoms
Editing bonds
Calculate mass and formula
Reaction arrows and plus sign
Text box
Select, move and scale
Rotation
Horizontal and vertical mirroring
Deleting and wiping