How to Thomson tcm420 router to a wireless router?

i recently got a broadband connection in my flat, and it's a Thomson tcm 420 router&modem for cable tv and internet, but without wireless possibility. in the meantime i acquired a TPLink TL-WR740N wireless router (not router&modem, just router), and i've been trying to connect those two so that i can connect via wifi in my flat.... i tried meddling with ip addresses, subnet masks, and so on, however something always keeps blocking my internet access... i'm a user of windows 7, and win says that i am connected to lan, (i supose the pc is properly connected to the wireless router), but further internet connection is not present... now, can anybody give me DETAILED instructions what should i do? what addresses should i copy to where? if i'm not wrong it should be some wan connection or something like that, right? any help would be much obliged. feel free to drop me an email to ivan.lesh.85@gmail.com if you have more detailed instructions, or, if you need some extra information.... thanks in advance!!!!