Landings - Lining Up Help

Hello everyone. I'd like to start off by saying I am 100% new to Flight Simulator 2004 and use it for 'fun'. (I know some people get upset when it is referred to as a 'game').
Usually when I use FS2004, I fly around on the big 737 Boeings. I don't know if I'm doing something wrong or if there is a tool to help me with this, but when I am in the air and spot an airport, I will tune into the tower and request landing permission. So that all goes fine and dandy, until it comes to the actual landing. How do you know if you are on the right bearing or are lines up correctly with the runway? Most of the time I have to judge it and end up crashing into the airport. Is there a tool for newbies or something?
Thanks in advance.
Regards,
Alexis
Usually when I use FS2004, I fly around on the big 737 Boeings. I don't know if I'm doing something wrong or if there is a tool to help me with this, but when I am in the air and spot an airport, I will tune into the tower and request landing permission. So that all goes fine and dandy, until it comes to the actual landing. How do you know if you are on the right bearing or are lines up correctly with the runway? Most of the time I have to judge it and end up crashing into the airport. Is there a tool for newbies or something?
Thanks in advance.
Regards,
Alexis