There are many ways to use threads. Which is approriate for your particular application will depend upon what that application is. Unless you describe your application, all you will get is meaningless handwaving answers. It is impractical for anyone to describe all the ways they can be used so that you can pick the appropriate one. Besides, you almost certainly wouldn't be equipped to make that decision up front.

I see from one of your previous questions that you've already read the nearly useless perlthrtut and are still none the wiser. (Don't feel bad, very few will ever learn anything useful from that document.)

If you are seriously pursuing help with creating a multitasking solution to your problem, then you will need to describe that problem in some detail, and explain what you are hoping to achieve by multitasking it.

One last piece of advice: Write a non-multitasking version first. Once you have a working, single tasking solution, it will be far easier to explore multitasking and: a) verify that the addition of multitasking isn't causing incorreect results; b) get a feel for whether you are actually benefiting from the extra complexity involved.