Threw is the simple past tense of the verb throw, which usually means to cause something to move through the air. (“Buddy threw the ball.”)
Through can function as an adjective, adverb, or preposition, each with a variety of meanings.
Through often suggests a passage from start to finish, or from point A to point B. (“Buddy walked through the museum.”)
Through can also mean finished, over, or completed. (“Buddy is through with school.“)
As a preposition, through means by, using, or as a result of. (“Buddy found out about the job through an ad on Craigslist.”)