Login as SCOTT and you can grant access on the tables to IYAPPAN. To grant selects, updates, deletes and inserts, use :

grant select, update, delete, insert on EMP to IYAPPAN;

You will then be able to access EMP from IYAPPAN using SCOTT.EMP

You can also create a synonym on EMP for IYAPPAN to avoid having to include the schema name when accessing the table.