Partial reactions in redox formation of rust
Bringing up rust seems to indicate confusion between the concept of corrosion and the concept of oxidation. Practically, iron corrosion is the breakdown of iron as a result of oxidation reactions.   

To explain corrosion, understand water can self-ionize producing hydronium, $H_3O^+$, and hydroxide, $OH^-$ as well as ionize small amounts of iron causing it to dissolve. The dissolved iron ions collide with the hydroxide ions to form iron hydroxide.  Iron hydroxide may fall out of the solution as it is not very soluble, or if the concentration is low enough the surplus of hydronium donates a proton to the iron hydroxide converting it to iron oxide.  

Oxidation, which is a more abstract concept, involves any reaction which results in the loss of an electron.  Instead of considering corrosion, consider other reactions.  In photosynthesis water is oxidized because it loses an electron.  In combustion, fuel is oxidized because it looses an electron.  

Chemical reactions can get extremely complex, so it may be prudent to master the language of chemistry before delving into the complexities of specific reactions.  Many reactions are described with the language of redox (Reduction and Oxidation) chemistry.