inp file extension

Dear All,
I am very new with MARK.
Could anyone please tell how create file for MARK. When I trying to open file with MARK, it saying that i do need .inp file extension.
But I have got text file with notepad.
Please help me.
Regards
Lutfor
I am very new with MARK.
Could anyone please tell how create file for MARK. When I trying to open file with MARK, it saying that i do need .inp file extension.
But I have got text file with notepad.
Please help me.
Regards
Lutfor