datagrid problems

Question

hi all. Can someone help me with this? I have a Datagrid, and i would like to doubkle click on a cell and open another form sending all the fields in that cell to the form for future work, how can i do this? Another thing, if i make the datagrid too large and i show only a few fields there's some space left at right, how can i make the datagrid complete automaticly stretch? Thanks.