Why am I listed as being offline for six days when I have been in the game every day ?

Because the Grim Reaper is coming for you? I dunno.

Offline where?

Your account here isn't linked to your game, if that's what you're asking.

Just because your playing the game does not mean that you are going on-line to Steam, just validating the game through the local client.

I may be misunderstanding you. But here goes. Open Steam. Go to your library page. Click on the upper left corner where it says "Steam." Go down to where it says "go online" or "go offline." If it says, go online, then click it.