Hi, Please explain me, that landing page is purely white hat seo technique or black hat seo technique.and how can i create a landing page for my site and what is the use of landing page for seo purpose.
It could be either, a landing page doesn't have an seo purpose in the sense that you're thinking. Think about its name "landing page" is a page that people land on from search engines or PPC, a landing page may be part of a mini-site or purely one page, of a page of a large site. The purpose is to get the visitor at the landing page to do what you want them to do.
search for 'landing page' and 'landing page optimization' on wikipedia. It has a pretty good description.
Landing pages have nothing to do with black hat or white hat SEO tactics anyway. They are used in advertising programs and are like ads or pop-ups for example and they are created for promoting products and other items and as mentioned, they are internal pages of the sites.
Landing pages can be White Hat or Black Hat. The purpose originated but trying to dominate SERP's. I see tons of landing pages on big sites. I have a few of my own.
Always stick with organic SEO. Avoid balck hat as it really brings you lasting benefits and will ultimately get your site banned.