Hi, i am beginer in baan ln6.1. can any body explain how to create and process MPS and MRP.

IN LN MPS/MRP are being replaced by Master Planning and Order Planning. An item can be Master Planned (if you check Maintain Master Plan in Plan Items) as well as Order planned. Master Plan will result into Plans that can be converted into Planned orders while Order Planning will result into Planned Orders. Go thru the help of the sessions and you will follow the entire procedure.

thank you rkathait, i have one more doubt, how to define number of units in a lot for a purchased item

Are you talking of lot size?
If you mean how does a lot size get updated in the lot details for a purchase item, then the answer is that it get updated when you receive the purchase items, attach the lot number to the receipt and then confirm the receipt - at this stage the lot size will get updated in the lot details. Do let me know if I did not get your query correctly.