Pronoms relatifs
Pronoms relatifs - French Relative Pronouns
Just as in English, a French relative pronoun links a dependent/relative clause (i.e., a clause that cannot stand alone) to a main clause. Que, qui, lequel, dont, and où are the French relative pronouns. There are no standard translations for these words; depending on context, the English equivalents are who, whom, that, which, whose, where, or when. In French, relative pronouns are required, whereas in English, they are sometimes optional.
The relative pronouns that is used is based on what its function is in the dependant clause (its part of speech) relative pronouns always come right after the thing that they are modifying (describing) and are followed by the dependant clause.
Que replaces the direct object (person or thing) in the dependant clause.
Qui replaces the subject (person or thing) in the dependent clause. Note that qui does not always translate as "who."
Qui also replaces an indirect object (person only) after a preposition (except de - see dont), including prepositions which are required after a given verb or expression.
Lequel or one of its variations replaces an indirect object (thing only) after a preposition (except de - see dont).
Dont is used to replace de qui, duquel, de la quelle, desquels, and desquelles. It also indicates possession.
Où is used for both place and time
To figure out what part of speech it is; look at the dependant clause and ask yourself the following questions:
Who/what is doing the action? Answer = subject
What is being "verbed"? Answer = direct object
What is the verb being done to or for? Answer = indirect object
Here are some excercices to help you with relative pronouns
http://www.quia.com/pop/150712.html