menu controling scripts

Script "A" shows a menu. Say button "B" on the menu is to start script "B" in the prim while button "C" will start script "C" if pressed and so on.
Where in Wiki is info on this? ALso, could I get a button to stop all started scripts in the prim?

The buttons on a menu repeat their text (B and C in your example). Scripts can listen for that text and respond according to their logic. Scripts don't typically start and stop, as such, instead they respond to events. For example, they might start and stop a particle effect in the event that they 'hear' a certain command but they are always running.

llDialog
llListen
listen

...are good points of reference for menus and sending commands that control scripts.

To explore what you term as 'starting' and 'stopping' you will need to give a little more detail of exactly what you're trying to achieve.

llSetTimerEvent
timer

...might be all you need but there are a lot of other possibilities.

HTH