[Bish0pQ]

Is this correct?
1.load combo (found few in this forum)
2. What is threads?
3. Click start and wait.
Is it compulsory to use proxies?

Pretty much that's all you do. To answer your questions:
[+] What are threads?
To explain as simple as possible, in your case, if you'd run 1 thread, you'd be checking account per account, 2 threads would check 2 accounts at the same time, 3 threads 3 and so on. Though your system only has a certain amount of threads. Usually running more than 10-20 threads doesn't do much.

[+] Do you need proxies?
Yes you need proxies in order to check those account, because after x amount of failed login attempts you will either need to fill in a captcha, or Netflix will block you (temporary) from logging in. This is why proxies are needed.

--> Tools for proxy scraping: Netghost (WastedWolf), GatherProxy... there are plenty around.