Such as this: http://www.masternewmedia.org/images/highway_id482808_size500.jpg . Is it possible that my camera (Fujifilm s100fd) can't do that, & if it's possible, what should I set the aperture or shutterspeed to? Thanks.
Yes, you can take pictures of passing cars at night with the headlights and taillights as long streaks of white and red with your camera.
You do NOT need a high ISO or a wide-open aperture. You DO need a tripod.
Your camera has a minimum shutter speed of 30 seconds. I did not see any mention of a "B" (Bulb) setting which would allow you to use a longer shutter speed but it really isn't necessary. You can use the camera's self-timer to control the shutter.
I use and recommend the FotoSharp "Day & Night Exposure Guide"
( http://www.fotosharp.com ). Although this exposure is for a "City skyline in distance" it will work equally well for car light streaks.
ISO 100
f4 @ 8 sec.
f5.6 @ 15 sec.
f8 @ 30 sec.
I suggest f8 @ 30 sec. to achieve the maximum blur. Of course you can experiment and try f4 @ 15 sec. and f5.6 @ 30 sec. Usually, though, the best results will be the settings suggested.
Find a location with minimal extraneous light, set up your tripod, mount your camera and give it a try.
Want to photograph floodlit buildings or fountains or outdoor Christmas lights?
ISO 100
f4 @ 1 sec.
f5.6 @ 2 sec.
f8 @ 4 sec.
f11 @ 8 sec.
f16 @ 15 sec.
Does the Guide work? You decide.
http://www.flickr.com/photos/drifter45h/899682567/ ISO 200, f8 @ 15 sec.
http://www.flickr.com/photos/drifter45h/899682797/ ISO 200, f8 @ 15 sec. Composed at 70mm, carefully zoomed to 210mm during the exposure.
You need two things... a tripod (or a flat surface) and a long shutter speed.
For a beginner like yourself, set your camera to S (which stands for shutter speed priority). Set it at 1 sec, then take a shot... look at the results, then make adjustments as you like.