Hi mahmoudsayegh2! Sometimes, knowing and understanding what SEO is, is not enough. You also need to have the time, dedication and strategical knowledge and insight . If you have the budget, I would suggest to consulting an agency to do the work for you. But don't go for the agencies who would promise #1 ranking in just a short period of time because it really takes a while (I'm talking about months). If ever you would need to go to an agency, go for Grow Digital Services. They can explain it further to you. Here's their website
http://www.grow.ae/. If you opt for other agencies or freelancers, do your research first!