How do I fix my problems?

sure sell it, (1/2 joking ) old post.
easy has only one path, that.
or learn how to find noise, with a stethoscope.
there are great books on finding noise, even toyota books.
here is one example'
no machine runs for ever, then fail and make noises.
Abnormal.
some are a danger to you car or engine.
so smart folks never ignore (1000x that on aircraft)
see scotty link here.

http://www.fixkick.com/NOISE.html

some noises are so hard to find the dealer has the car crushed
and gives you a new one. (loose metal chucks in frame? or spoon from union hack.)

here are few components that can cause such problem.Its advisable to click the link below and follow the troubleshooting to correct the problem.
Engine makes noise? http://howtobyme.blogspot.com/2011/12/engine-makes-noise-and-cooling-fan-belt.html

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Chirping sound coming from engine? http://technoanswers.blogspot.in/2012/01/chirping-sound-coming-from-engine.html
--------- Vehicle making Clunk Thump Thud noise? http://howtobyme.blogspot.in/2012/03/vehicle-making-clunk-thump-thud-noise.html

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Car Engine Overhaul Tips? http://vwrepairhelp.blogspot.com/2011/11/car-engine-overhaul-tips.html

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HOW TO PERFORM A BASIC ENGINE TUNE UP-OIL CHANGE
http://schematicsdiagram.blogspot.com/2011/08/how-to-perform-basic-engine-tune-up-oil.html

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Rattle noise from engine? http://whatisbyme.blogspot.in/2012/05/2005-toyota-corolla-rattle-noise-from.html

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These will help.
Thanks.

The light is on because of oil pressure being low in the engine, do not drive this until the source of this low pressure is corrected. The noise you hear is engine parts lacking proper lubrication. Have this fixed ASAP or you will destroy the engines bearings, a $4000.00 repair on this car.

Any noise must be first inferred for the point of generation. So in this case I think as you mentioned it must be from the engine and the options are to check if the rattling is there while on the move or if the enigne is revd.
If while on the move , check the wheel bearings, the suspension parts, mudguards, muffler/exhaust and steering sections.
If while the engine is revd, it can be the water pump/alternator, radiator fan, idler pulley or the main pulley belt.
Observe, ask a friend to drive while you locate the source of noise to confirm the section.

READ THIS (happy ending so far...):
audi a4 2L turbo quattro, manual transmission with 98,000 KM. Perfect conditions, no oil leaks whatsoever.

Left the car off for two weeks in very cold weather (-10C down to -25C). When I restarted, it started immediately but with heavy rattling noise due to camshaft adjuster not getting enough oil pressure. After 3 minutes of warming up (outside temp.: -12C) at very low rpm (below 2,000rpm), I start moving the car. Still hearing heavy rattle noise. As soon as I pass 2,000 rpm, I get a scary red warning, low oil pressure. Turn off the engine immediately. In 1 minute, I re-start the car and the engine lights check ok, so I drive in first gear super slow (1,200rpm) hearing the same rattling noise. After another minute, finally the noise all the sudden disappears and the car starts running just fine.

Called Audi dealer and they told me that in extreme weather conditions, I should warm the engine for 10-15 minutes if necessary before start moving.
Take away: luckily, I didn't screw up the engine since I was using it at extremely low rpm (easy to do with clutch and manual transmission) until the oil reached full pressure. I am pretty sure now that the problem was leaving the car off for such a long time in freezing weather. All the oil flows back to the bottom, and when I restarted it, the cold oil with high viscosity took a long time to reach all the parts of the engine, specially the camshaft adjusters that are actuated by using oil pressure. Next day, the car started at -9C perfectly without making any noise (as usual). Basically, the longer you leave your audi in cold weather, the longer you might hear the rattling noise until the oil reach full pressure inside the engine. My car took 6 minutes to fix it after couple of weeks in cold weather. This makes sense to me; in fact, in the past I only heard the rattling noise after leaving the car off for a couple of days in the winter.
So far, this has had an happy ending....

a light tapping noise is quiet normal .Use a flushing oil before you change the oil and filter.then use 10/40 semi synthetic(as recc by VW)when engines at operating temp run at 3500 fo 30 secs,this will "charge" the hydraulic tappets,a cold engine has a valve rattle for about 15/20 secs but if longer then cam followers faulty.normally at 120,000m(roughly)
please leave feedback..

Strut mounts

4.0l's are notorious for valve rattle on cold start-up. There is really nothing you can do to make it go away short of completely replacing the valve train in the top end, and that isn't a permanent fix. It's is an top end oiling issue from the factory. Just don't race your engine on cold start-up until the rattle stops.

The rattle in the transmission sounds to me to be more of a loose dust shield/heat shield around the transmission or exhaust than a mechanical issue.

Its a dealer fix problem. Its under warranty take it back and tell them to fix it. If they cant hear this noise then ask to have a tech. ride with you and when u hear it point it out to the tech.

I had the same problem! I crawled underneath the car and discovered that a heat shield on the exhaust header pipe was corroded and rattling against the exhaust pipe. (Before the muffler)
I removed the portion and clamps and solved the problem. Give it a try.