Table maintainance generator

Hi,

I have a requirement in which i have to add a new column to an existing ztable and update some values in it.

I have created the column and i now need to add entries thru sm30.But i donot get the new field there.

i wanted to know whether any additional configiuration should be done for this. the existing table has a TMG already, what can i do to enter values into the new field? please guide