>I am trying to convert a container into a class but I am not sure about how to make the table and field names as variables and pass table and field names as parameters from the calling program. Please HELP!!

Any class can accept parameters in its Init event. The calling program uses CreateObject to send the parameters:
Thisform.oContainer=createobject("MyContainer",Parm1,Parm2....)
So, you can send table/field name as Parm1,Parm2 here, e.g
Thisform.oContainer=createobject("MyContainer","mytable","myfield")
***Mycontainer.Init event
LPARAMETER cTablename,cFieldname
Select &cTablename.
IF &cTablename.&cFieldname=...
ELSE
ENDIF