There are quite a few events that make up this very technical story. It's pretty difficult to pick only three events but I'll try.
1. Winston begins his diary. This is Winston's first outward act of rebellion. He knows the consequences but he does it anyway. Winston needs to feel something, anything. His diary is the bginning of his very dark and ultimately futile journey against the Party.
2. Julia Hands Winston the note. The note says "I love you" . This says so little and yet so much. This is Winston's Introduction to Julia and brazen rebellion. Besides a lot of sex, Winston begins to formulate dangerous ideas (to himself) of rebellion, the brothorhood and O'Brien.
3.Winston yells "Take Julia". This is the final point of Winston's re-education. Winstonhas come full circle. Winston has progressed from a nervous man with a diary to actual rebellion and finally to a shell of his former self who nw loves BigBrother.