Hi there. Have you tried logging into your Steam account first before installing Civ?
If you can't seem to log on to steam, tried re-installing it? If it still won't log on for some reason after re-installing, and it's not your connection, go into your steam folder and look for any file named ClientRegistry.blob, then delete it. Then try opening steam again. It should re-update and hopefully let you log in.
If Steam lets you in and it's not installed (either not in your games list or it's text is grayed out), then you can try re-installing from the disc and see what happens (or just install it from Steam itself if your connection is good). If it's listed in the game list as installed for some reason but it won't play, you can go for two things. If your connection is good, right click on it, click Properties, then go to the Local Files tab. Click "Verify integrity of game cache". This will force Steam to check your game files. If it finds anything wrong, it will download any broken parts (or the whole game if it's not there). Or you can just right click then click "Delete local content" then re-install from scratch.
And one last thing. Game files for steam are under the Steamapps folder. Non-Valve games are usually under the folder common.
I hope that helps.
