Depends on how old. The most recent tube TV I owned actually had HDMI but that is unusual. Most tube TV's only have RF and composite AV inputs. There are RF modulators and VGA to AV converters. You can get your computer output on computer but remember that standard definition TV is much lower resolution than your computer display. It might be ok for games but otherwise it is probably not worth the bother. Newer HD 1080p TVs go up 1920x1020 resolution which is pretty decent resolution even for computers.
I'm not sure what you mean by "Tube TV" ... here, that means one of those old "box-y" tv sets and they don't typically come with computer accessibility. If it's one of the newer ones, you should be able to figure out what wires you need by checking the back of the television set.
computer to a tv ? . You need a wire . its nothing more complicated than that .
You need a HDMI wire to connect both, I actually have to buy one of these
what kind of wire?