Great Fishing

I Have A Question About Fishing. Im 17 And Im About To Buy My First Fishing Pole But I Want To Go Cheap Maybe Around 20-30 Bucks. What Size Is Appropriate For My Age? And Do You Recommend A Specific Brand That Cheap Prices And Good Quality? I Plan To Go To Walmart To Buy My Fishing Rod, So Would It Be Better To Buy A Rod/reel Combo, Or Buy The Rod And Reels Separately?