You do not require to know the reviewers (actually you should even avoid people you know well). You just have to think if those people would be able to have a full understanding of your paper. Your own bibliographical list is a good starting point.

Ok. So I just pick up anyone who i think have expertise in that particular field even though they do not know their name have been choose for reviewer. is that so?

Yes it basically is... After that, it's up to them to decide if they are willing to review your paper...

Ok.. Thank You so  much

 Dear

a good reviewer for a manuscript:

They have expertise that is specific to your manuscript. This should be obvious, but some authors make the mistake of suggesting reviewers who simply possess a lot of general knowledge in the area or who are highly distinguished. The reviewer has recently published in the area. The individual is still active. A simple web search should be sufficient to verify this. Try to identify the names and current contact info for at least three individuals. The more you can list, the better. Begin with the list of individuals who appear in your list of references, in particular those that are closest in nature to your manuscript. Conduct a search on Google scholar and any other databases you have access to. Hopefully you did something like this before ever beginning your research, but it is possible that something was published recently that you missed. Then go to the home page for the journal you plan to submit to, and search the journal’s page for the keywords that appear in your manuscript.

Identify the individuals that were primarily responsiple for or directed the research for the results of the above, and verify that they’re still active and that their contact information is current. If your manuscript covers several different topical areas, try to identify at least one reviewer for each area. It is OK to suggest high-profile or highly-distinguished reviewers, provided that they are heavily cited by your manuscript or that they have expertise that is particular to your work. However, your list of reviewers should not consist solely of highly distinguished individuals. Avoid suggesting reviewers who are not at arms-length from you or your co-authors. This includes graduate advisors, people in your current department, or any others with a conflict of interest. Provide a justification for each reviewer. Of course, following the above guidelines will not mean that the editor uses any or all of your suggestions. However, if you follow these guidelines, at minimum you will have performed your due diligence with regard to properly citing the literature.

Good luck

When journals request you submitnames f potentialreviewers, more often than not they use these suggestions to increase their pool of possible reviewers on a subject and not necessariliy invite this reviewers to review your manuscript. This being said, it wouldalso  be advisable to atleast google the reviewers and decide on face value if you are comfortable with him or her reviewing your work,  peradventure the journal decides to follow your suggestions/ You dont want to hand pick the reviewer thats gets your manuscript rejected.