setup intercomapnies

Would anyone tell me how to setup intercomapnie transactions(my system has only 2(DAT,SMY) companys).

You should not use DAT company for transaction purpose. Its a defualt company.
You should have one more company to start inter company setups and transactions.

What does your intercompany transactions include???

You should go thourgh the Inter company funtionality which AX covers and required setups - you can download the required document resources from partner/customer sourceā€¦