How to default values on screen using FREE_SELECTIONS_INIT

Hi Experts,

I have the following requirement :

We have developed a screen on which there is a button. On click of the button, a dynamic selection screen is generated using the functions FREE_SELECTIONS_INIT and FREE_SELECTIONS_DIALOG.

I want when the selection screen is generated for the first time, the fields on it contains some default values taken from a table.

e.g. If Screen has fields MARA-MATNR, MARA-MTART, MARA-MEINS then MARA-MEINS should be defaulted with a value 'EA'.

I have tried a lot but could not find a solution to it.

Kindly help me out as this is very urgent.

Points are guaranteed..

Thanks in advance.

Regards,

Himanshu