Welcome Bob.
I've found that the easiest way to learn a little about a train such as yours is to look up the number on EBAY. For example I typed in "Lionel 8204" and a bunch of examples came up.
In a minute I learned that this engine was made by Lionel (MPC) in 1972, O27 gauge, Forward/Reverse "E Unit" (NO neutral position) and a early "Sound of Steam (static sounds to sound like a steam engine chuffing) tender.
I'd take the shell off of the engine and tender and wash them in a diluted solution of dishwashing detergent and water, using a soft tooth brush. Dry well and, for a little sheen, spray and wipe down with ArmorAll. While the shell is off the engine lube the motor with a couple drops of oil and the gears with a lube like white lithium grease. Re-install the shells. Clean the wheels with a Q-tip dipped in rubbing alcohol and oil the turning points on the axles.
Your train will run on both O and O27 profile track. If your track is not rusty, just dirty, I'd clean it by scrubbing loose dirt off first with a fingernail brush (a brush about 1 inch wide and 3 inches long) will work well for this purpose. I'd then polish the railheads with a plastic scrubbing pad (the green kind that you can get bunch for at the 99 cent shop will work fine). Finish with some rubbing alcohol on a folded paper towel. Don't forget that the connecting pins should also be cleaned. Do not use steel wool.
IMHO, if the tracks are rusty discard them and get new ones. Good used track is available at train swap meets, EBAY and you may even find them at some hobby shops.
The above are just the basics - search this forum for more details. UPDATE: brianelO27 provided some great info as I was typing this post
Good luck, keep us updated.
