night shot help

Ok, i'm an absolute rookie here. I've been taking shots with my Rebel for some time now and so far had some good ones with good lighting. Not that long ago i got myself 430ex flash, which is very nice when taking shots of objects in normal lighting conditions. However, couple days ago i was taking shots of my friend in Grand Central, and was trying to get both - my friend and some background, but ended up taking the 430ex off the camera and using built-in flash in "night" mode. How do I use the 430ex to take a good night shot so that background doesn' disappear? I know it's probably something simple, but i just cannot figure it out

Thanks in advance!

I put the camera in M and set up the shot based on the ambient light to get the best exposure I can without the flash. Then the flash will light the foreground subject. Just watch that the shot you meter can be hand held without a problem.

If you put the camera in Night mode you can check the f-stop and shutter speed it has selected to use as a guide.

And if I've got this wrong someone will straighten us both out.

Welcome to the forums. It's a great place to learn.

That's probably good advice. Also you can try Av mode...that allows the E-TTl to try to match the background with the subject. This might lead to slow shutter speeds, so a tripod or a steady hand is required.
In Av mode, set the f-stop at the lowest number your lens has, btw.

1/60, f/5.6 in Manual mode.

Start there and adjust if needed (probably won't need to).

Get a Lightsphere II (it's amazing).

Good luck.