When i start X i get a menu with all the different kinds of managers to choose from and i always go to fluxbox i was wondering how would I get it to start in fluxbox automatically?

Since Vector is a Slack copy, iirc, this should work. Do both for the heck of it.

First, start in runlevel 3. At your LiLO prompt, rather than just hitting enter, use the tab to choose your image name and then add a space and then init 3 -- for example:
then after you login type "xwmconfig" and choose Fluxbox. After that you can type "startx" to see if Fluxbox starts with the X server. Then just reboot as normal and let it boot into runlevel 4. This time from the login menu make sure you choose Fluxbox, and it should default there on your next reboot.

If this doesn't work, then something in Vector is broken, or either different, than Slackware IMO.

I did what you said and it worked great for all the other windows managers but whenever i tried to boot fluxbox its a black screen and the mouse is a black x and thats all that happens, i looked at the init file for fluxbox and it looks fine, i dont understand whats goin on.