does anyoen have any info / story's about these criters as im camping there for a few nights with my tour group and im pretty scaired!
Yosemite Bears
Here are some links that may help you:
National Park Service - Yosemite National Park Bear Safety page:
Bear Safety
American Park Network - Yosemite Flora & Fauna page:
A Bit About Bears
The Bear Etiquette Site:
Bear Country Etiquette - Yosemite
Yosemite Fun page: (Good info w/ a touch of humor)
Bears
Tens of thousands of people visit Yosemite yearly without incidence. You will be with a tour group so you will have the added protection of safety in numbers. The bears want your food - not you. Bears can be very scary, but your neighbors on the next door campsite will probably be scarier. (Kidding!) There are Park Rangers there to explain the do's and don'ts for bears and you will (most likely) be camping in a designated camping area.
I have not been to Yosemite personally, but have been to Yellowstone National Park. When there has been a bear sighted in any particular camping area, those sites are closed for use temporarily and campers relocated to a different area of the campgrounds. I'm sure the procedure is similar, if not identical, in Yosemite. The National Park Service's regulations are pretty standard across all parks, with some alterations/additions that pertain to each park's own ecosystem.
Enjoy your trip and your visit to Yosemite! Everything will be fine. Just remember not to feed marshmallows to the bears with your teeth. They are greedy and love marshmallows! 
Just don't watch Grizzly Man before you go out there...
yer ive read a review for that and i will defently not watch it - il watch it when i get back tho as it sounds intresting - poor fella!
cheers for the advise!