Hey,
First of all you need to make a YGOpro account which you can do here:
http://www.ygopro.co/register.aspx?returnurl=%2fDownloadmembers.aspx
Then you can log in and download it here:
http://www.ygopro.co/login.aspx?ReturnUrl=%2fDownloadmembers.aspx
If you need any more help just ask