Stacked histogramme, can I show "actuals" on it?

you are asking two different quesitons here

can you to show actuals on a non stacked ?

the answer is yes 

can you show stacked actual on a histogram ?

it is easier to do in version 8.2 than 6.2 but it can be done.if you have the resouce codes set up then its easy

to show them stacked 

view show on botom resource profile

in the lower left hand window click on the upside down triangle where it says Display and select Group and Sort By

next select customize

in the group by put in your resource code in there you can also change the font and color for each code 

in the right hand window right click and select resource Usage Profile Options and select actual you can do this for either the units or the costs 

as another method what you can do is to assign a role to each of your resources

then view show on botom resource profile in the lower left hand window click on the upside down triangle where it says Display and choose Select View then By role

then on the rigth hand side rigth click and select stacked histogram 

now right click and select role usage profile options 

this is where you give the roles the diffierent color and patterns that you want to use