Pokemon Heart Gold - help.?

so, i have 6 badges ( violet city, azalea town, goldenrod city, ecruteak city, olivine city & cianwood city) and i'm pretty stuck.. i now own the safari zone and all that, but i've had mixed answers on how to 1) get to Blackthorn City and 2) sort out the team rocket radio tower business in Goldenrod city.. if you know please tell me how to do it because i'm so confused and i can't move on in the game :(