1.how i can get all customers.

Put this code in a customer form method called RefreshGrid(). Call this method whenver you want to change the contents of the grid.

LOCAL ldStart, ldEnd
ldStart = thisform.pageframe1.page1.text3.value
ldEnd = thisform.pageframe1.page1.text5.value

SELECT inname, billno, SUM( total ) AS bill_total FROM Mstr WHERE ;
  BETWEEN( datein, ldStart, ldEnd ) ;
  GROUP BY inname, billno ;
  ORDER BY inname INTO CURSOR qTmp
SELECT csrBillTotals 
ZAP
APPEND FROM DBF( [qTmp] )
Thisform.pageframe1.page1.grid1.refresh()

2.how i can see the result via grid
This goes in the Load() method of the form. Note that you will need to change the data types I have defined so that they match the data types of the fields in your Mstr table.

CREATE CURSOR csrBillTotals (;
  inname C( 30 ), ;
  billno I, ;
  bill_total Y )

Set the grid's RecordSource to csrBillTotals in the form designer

Have you obtained any VFP reference books yet?