Understanding the location of electrons and being able to draw the curved arrows that depict the mechanisms by which the reactions occur is one of the most critical tools for learning organic chemistry since they allow you to understand what controls reactions, and how reactions proceed.
Before you can do this you need to understand that a bond is due to a pair of electrons shared between atoms.
When asked to draw a mechanism, curved arrows should be used to show all the bonding changes that occur.
A few simple lessons that illustrate these concepts can be found below.