Let's make these sentences passive
1. Henry posted the letter
2. Sally bakes a cake
3. Jeff wore the blue shoes
Step 1: Make the object the new subject. Start the sentence with it.
Step2: add a form of "to be" that matches the tense of the verb and the new subject.
Step 3: turn the orginal verb into its past particple form (voltooid deelwoord)
Step 4: add "by" and the person.