I wanna play classic tbc or vanilla? Where and how to start?

I wanna play classic tbc or vanilla? Where and how to start?

Click on your wow launcher and click on the the game version.

You will see 3 modes retail/classic and classic cata.
Choose classic and join the normal realms or hardcore/discovery.

Hello! Thank you for answer. But is still possible to play tbc ?

There is currently Classic Era (Vanilla), Classic Hardcore (death is permanent), Seasonal Classic is currently Season of Discover (SoD) which is Classic with a twist, you get glyphs and get abilities from them that aren’t usually avaiable in Classic or to your class. Then last but not least we have Cata Classic which is currently in prepatch.

It is not possible to play Classic TBC or Wrath. They didn’t keep dedicated realms for it, I think because Era died so much after TBC was launched.