Manipulate Table Data...?

Hi Im learning C# lately. Im working right now on a project that should help me learn some new stuff about C# programming... I'm programming a simple accounting software, that can be used by small businesses, especially by small shops. This software should register products, it will have a form to sell them and pay bills, a form to use for furnishing, and will also make reports and such stuff... I made the register form, but now I'm having some problems with furnishing form. For example, when the store owner buy some products (furnish his store with products) I want to register them on furnishing form, but he will be able to register these products only if they're registered first in the Registering Form... In the furnishing form he will only need to enter the product Barcode and the Quantity, and these automatically will be added to the database (furnishing table) and the other details for the product will be taken from the other table (registering table)... I usually use LINQ's to take a row from a table, for example, a row where given barcode match, but i dont know how to take a specific cell from that row, and send (or add) the data to another cell on another table... Hope u can understand what im asking ... Im sorry for my bad English... Hope ill find some help too.. thnx a lot...