Well, Qassim. Posting a question here is a good start. You can go to Find a langauge partner first. Cause you want to learn English, then select English speakers. Both native and ELS speakers are good for learning English. And while you check on someone's profile for example, you will find a list of options at the right hand side of the webpage,
Add to Friends, Send a Mail, Chat Now and Report Concern. You can click on Add to Friends, and then send one invitation. After the recipient accepts your invitation, you can start language exchange right away by using Chat Now of italki, Skype or MSN.
In Files and Resources, you will find some good learning materials for learning English. If you have any questions while learning those resources, post a question here in the Answers.
Join a group is a good choice as well. Everyone is here to share and learn. And for Language Index, click on any of those languages will lead you to the complete lists for both native speakers and learners.
Hope those are what you need for using italki.