How to Use BAR Code Printing.

Hello People.

I have got an Task of making the label printing with the help of "BAR CODES IN SAP".

Actually i don't know any thing about the bar code printing in "SAP".

So is there any one who can answer my question on "SAP BAR CODE PRINTING"

1.)How does this bar code printing works . ????

2.) How we are going to use this in a real time environment ... ???

3.) What is the layout of making the BAR CODE PRINTING in sap and who we are going to assign it to the material in the plant.?

4.) What are the necessary programs and MPP are required in BAR CODE Printing.. ??

5.) What will be the affected regions where this amendment will hit..????

Thanks in advance...