Tools, Sharpening and Power Machinery - Soldering gun--What does tinned mean?

I have a Weller soldering gun that I can't seem to get to work. It says in the directions that the tip should be tinned. Unfortunately it doesn't explain what that means? Also, how long does this thing have to heat up in order to work? It is a multi-purpose, 75 watt standard. Thanks.

Tinned refers to the process of coating the tip (or any other object)with a light application of solder. With a new tip, I turn on the power for a few seconds to warm it and dip in the flux. Then remove the tip from the flux and continue heating till it melts the solder being held against it. Rub off the excess molten solder with a quick swipe from a cotton rag or paper towell. I find that it is sometimes necessary to re-tin the tip if it gets overheated and corrosion occurs. In that case, just sand or file the tip down to bare metal and repeat the process.:) Oh, the heat-up time for a soldering gun should be just a few seconds - 10 to 15. If more is needed, check the attachment of your tip to the gun. Are the nuts (or screws) tight? Is there corrosion which may limit a good electrical contact there?

Thingy, Thanks for the assistance. Guess I better buy some flux.