[flexcoders] adding columns to datagrid programmatically

[[p e r c e p t i c o n]]

dear gurus and other experts...
how does one add columns to a datagrid programmatically...and also how so i
make editable right inside the grid? for example what if i wanted to  have a
column with a hyper link another with a numeric stepper another with a text
input...
thanks
percy