The trick is to keep your ISO as low as possible (to reduce the grainy look) a high iso will enable you to use lower light but at the expense of grainy images.
Stick your iso at 100, aperture (f number) as low as pos 5.6 etc and put your camera on a tripod then adjust the shutter speed accordingly. if it is too low (under 50) then increse your iso to 200 or 400 and try again.
In my experiance you just need to experiment, keep trying and use different settings.
have a look at my website for images i took whilst Travelling.