I need to pesent a formal business plan, but I haven't done this before.
Can anybody else teach me how to write a business plan or tell me where can I find the sample of it?
Thanks!

Two really great places to get help for something like this are http://www.sba.gov/ and SCORE "Counselors to America's Small Business"

There are samples on those sites which you could tailor to fit your needs.

Do I need to pay for it if I search these two webs?

I know that you don't on the first one. I don't think that you do on the second one. But, I'm not sure since I have not really used it as much as the first one. I just know that both of those sites are excellent!

A couple more options. Trump University has a free Business Planning Course or you can get QuickPlanner Plus which comes with an excellent how to guide.

Here is a link to another site that I just found that seems to have a lot of free business plan templates.

Business Plan Software and Free Sample Business Plans - Bplans.com