How long is a opened bottle of wine good for?

[Innkeeper]

The best way is to find a glass vessel the wines just fits in, cork it, and put it in the refer for a day or two at best. If you are a half bottle at a time type, a good idea is to have a used half bottle on hand and a cork recorker. When you open a new full bottle, fill the half bottle first, recork it, and place in refer. Then enjoy the rest of your bottle at table.

This board is a good place to learn about wine. They are also very good books recommended here (try "wine books" on search). Your library, and online book stores like Amazon and Barnes & Noble are also good places to look.