how to add items(parent,child) in treewidget on clicking of a button

[jyoti]

hi all
my query is:
i m creating a form(attached)
when i enter name in line edit after clicking of enter first value should become parent
then clicking of sub-item button enter text in line edit should become subitem of paricular parent
n when we click remove button particular selected item shud be removed.if parent deleted automatically the sub items deleted from tree

plz help me as soon as possible

thanks in advance