Ok!
An indirect object receives the object and comes between the verb and the direct object. For example, "I gave her a flower". In the sentence, "her" is the indirect object because "her" is receiving the object, "flower."
A direct object receives the action of the verb. For example, "She needs help". In the sentence, "help" is the direct object because it receives the action, "needs". It is what is needed.
Another example: "I like cake." "Cake" is the direct object, because it receives the action, "like".
The object of the preposition follows the preposition. "At school, I took a test."
In this sentence, "school" is the object of the preposition because it describes where and completes the preposition.
I hope this helped! If you're still confused, just send me a message! :)