(which is my favorite sport) how do i put this in a complex sentence

If you need a sentence of your own, you can use this clause Which is my favorite sport as a non-restrictive relative clause to give some additional information about a sport. For example,

Cycling, which is my favorite sport, has never been absent from the Olympic program.

Explanation:

A complex sentence is a sentence that contains an independent clause and one or more dependent clauses.

A dependent clause is a group of words with a subject and a verb. It does not express a complete thought, so it is not a sentence and can't stand alone.

Which is my favorite sport is a dependent clause as it cannot stand as a sentence by itself.

So you need to add an independent clause to have a complex sentence.

Cycling has never been absent from the Olympic program is an independent clause. You add your clause which is my favorite sport simply  to give some additional information about cycling.

what do you mean

explanation: