I need to create a secure internet wireles network and am not quite sure how?

I have asked a similar question but did not receive a sufficient answer. I have a new Windows Vista computer that is connected to a cable internet modem (Motorola SB5120) that is then connected to a DLink router so that I can have wireless internet on my laptop. I want to create a password protected system so that neighbors, etc. cannot access internet through my wireless router. I also am concerned with hackers, etc. Please include step by step instructions for me to do this. Thank you!