Explicit Locking. Please someone HELP me!!!

I'm doing some study on the way locking works in DB2 UDB database.
I want to prove that DB2 does not allow the application to gain control on
locking mechanism. The example provided is on parent/child relationship.
This is what I want my application to do:

xlock parent_table where <condition>
if status <> 0 then {failed to lock the records}
begin
set parent_flag to false
display message
end

xlock child_table where <condition>
if status <> 0 then {failed to lock the records}
begin
set child_flag to false
display message
end

if parent_flag = true and child_flag = true then
begin
delete child_table where <condition>
if status = 0 then
set del_child to true
delete parent_table where <condition>
if status = 0 then
set del_parent to true
end

if del_parent = true and del_child = true then
commit work
else
rollback work

How you code this in VB? I really appreciate if you can provide me with
the sample program as I'm reaching a deadline. I'm not a VB programmer
and since VB is one of the most popular tools nowadays, I really need it
to support my case.

Any feedback is welcomed.

Best regards.