Stumped with how to filter the data I need for a report

I am designing a report using Visual Studio and am stumped on how I can filter in a specific column to get the data I need.

I built the query/Dataset to pull the part inventory information and sort/sum by Pattern/Color but for a specific column of information, I only want to see the inventory amount for part names that start *like* "FS AH".

So, these are what the parts would be from the query:

Part Name                       On Hand QTY         Pattern/Color

FS AH004                              10                         BIBA ACORN

FS CY004                              20                         BIBA ACORN

FS AH004                                5                         TEAL CHEST

FS CY004                                3                         TEAL CHEST

My Report shows this:

Pattern/Color               On Hand QTY SUM    

BIBA ACORN                       30  

TEAL CHEST                         8                        

But, I want the "On Hand QTY" to only show the quantity for parts that start like "FS AH":

BIBA ACORN                       10

TEAL CHEST                        5

I must be missing something that is probably easy so I would appreciate any suggestions.  I am hoping that I can filter somehow by using an Expression in the report.

It currently is the following but there must be someway to filter on Part Names that starts like "FS AH":         =Fields!AVAILPHYSICAL.Value