how can i change axis i.e. i need to show furniture,office supplies,technology dimensions on the x axis in side by side bar chart,and i want to remove space between bars.

Like this?...

Here I've put a condition in the formula

IF YEAR([Order Date]) = 2011 THEN

    STR(YEAR([Order Date])) + '

    '+[Product Category]

ELSE

    STR(YEAR([Order Date]))

END

so it only displays the Category for 2011 (this is not very dynamic, but we could put an index() calculation in so that it dynamically only puts the Category label into the center value, or the 1st...but hopefully you can extend the logic to fine tune exactly what you need.

I've also done a bit of formatting on the Column Grid, to more clearly display each Category.