this question is very general and very basic. You will not get a lot of help when you post a question like this.
I suggest you use one of the example databases that comes with the product and check how that is build.
Look in the field definitions for fields that are set as globals, then look in the relation diagram how they connect to other tables, then read the scripts step by step how they are used.
You should be able to learn a lot just from looking at the examples.
Then when you are stuck with a specific issue, post a more detailed question.
A global field will have data that is the same for all records, just add one field with a global storage option, enter some data and cycle through all records, you will see the value is the same in all records.
It is often used for filtering subsets of related records.
Thank you for answer.
I Attach my file, and have some question about it?
1- How I can use of global in my database,I mean wich of my field should change to global.
2- I want to know summary of a product for buy in report, I design it but I see a report like :
invoice 1 Product::A Qty:5
invoice1 Prodcut::B Qty:6
Invoice 2 Product::A Qty::3
I want to see a report like: Product::A Qty::8
Stuff.fp7.zip 9.8 K