How Do I Find Direct, Indirect Objects, And Object Of A Preposition?

The direct object is affected by the action, eg "Jim threw the ball." The ball is the object.

The indirect object is the thing/ person to or for whom the action is done, eg "Jim threw the ball to Sally." "Jim threw Sally the ball." Sally is the indirect object.

Any noun or pronoun after  a preposition is an object (can be called a prepositional object) eg "We sat on the chair" - the chair is the object.

These exercises may help.