multithreading in .net

[atrocious]

hello every one i have made a fake hits
generator. i have tried a lot to
multithread it but i cannot so i decided to use
background worker to make my
ui thread responsive well it doesnot goes well
cause it is still slow i just want
to make it like i can control number of threads
by a trackbar so if the value of
trackbar is on 20 then 20 threads should be
created and they check 20 proxy
simultaneously then switch to another 20
proxies
i am new to
multithreading so i need some help to edit my
code so that i could learn

multithreading

i am also uploading 2 pics one is of mine and nother is of that project of which i want to make