Own Atari 2600. Atari not

Question

Own Atari 2600. Atari not responding to television. (FUZZY SCREEN)One of three problems:1. I AM NOT CONNECTING SYSTEM CORRECTLY TO TV. please instruct me how. parts i have are: Radio Shack RF Modulator ATARI PART # c016353 Adapter b/t power source (wall outlet) and ATARI console. 2. THE CONSOLE IS DEFECTIVE. how will I know? is there a visible "ON" light when plugged directly into wall?3. NO CONNECTION DUE TO WRONG ADAPTER I thank you in advance for your expertise resolve to this frustration.