A family of Microsoft relational database management systems designed for ease of use.
I'm going to suggest you read about declaring variables and Dim statements. Here are a few links to get you started...
Declaring Variables
http://msdn.microsoft.com/en-us/library/office/gg264241.aspx
Declaring Variable by Chip Pearson
http://msdn.microsoft.com/en-us/library/7ee5a7s1.aspx
Dim Statement (Visual Basic)