I am a new driver and I know very little about mechanics. Could somebody help me with my silly questions.

My 92 190E speedometer pointer vibrates at speed below 40. What does a vibrating speedometer mean?

There is a indicator turned on whenever I start my engine. The indicator looks like a tank with some water ripple. What does it indicates?

There are 2 tanks on the left side of the engine when I am standing in front of the car. One of them is a small 'brown' tank, and one of them is a big white tank. What are they and what I should fill in?

There is a position, that looks like a <-P->, at the leftmost position of the headlight switch. What is it?

Is there anyone kind enough to tell me where can I get a owner's manual for this car, as it is much more complicated than my previous cars. (I owned a Mazda and a Kawasaki)

Cheers,
Barry

big white tank is winshield washer fluid with a plastic cap on top of it. Small brown tank (clear but stained) is the radiator fluid (antifreeze) there should be a cap with a number engraved on it on top of it.
Shaking speedometer sometimes means that your missing some teeth on the cable cog, mine has been doing it for awhile now.
<P> is the parking light, I believe this option changes depending on country.
You can order the CD for this car here at the partshop page or get a Haynes manual which isn't as detailed.

Welcome to the Shop by the way!

The "tank with some water ripple" icon in your instrument cluster is the low engine coolant level warning light. If the light remains on after the engine is started, then check the coolant level in the coolant expansion tank. If the coolant level is within normal limits, then the coolant level sensor located within the tank is most likely faulty.

Speedo needle vibration is from the speedo cable being stretch TOO much. When disconnecting the cable on 190's, it MUST be disconnected from the trans first. If not it will be stretched & then needle shakes.