Hi Sunny,
The code for setting the value in EditText is as follows:
Dim oEdit As SAPbouiCOM.EditText
oEdit = Me.oForm.Items.Item("UIDofTEXTBOX").Specific // UIDofTEXTBOX is the Unique Id of TextBox
oEdit.Value = "TestValue"
Hope it helps.
Thanks & Regards
Ankit Chauhan