Welcome to the forums.
The answer to your first question is speak and listen to English all the time, and practice practice practice.
As to your written work: capital letters are used with the first word in a sentence and with proper names; one space is needed after a punctuation mark.
Nb - in English it is "Saudi Arabia" and "Mecca"
saudi Arabi Is One Of The Countries Which Are In the Middle East. It has a large Area . It Limmited Between 8 is bordered by eight Countries , From North There Are. In the north are Iraq And Jordan, from South There Is Yemen , in the south is the Yemen, from West There Is on the west is the Red Sea,from East There Are Emirate ,bahrain,qatar,oman And Kuwaitand on the east are the Emirates ..... Saudi Arabia Has has a lot Of Oil And It Has Quarter Of Reserve Of The World. The population Of Saudi Arabia Is About 28 Million. The re ligion Of Saudi Arabia Is Islam And It Has Two Holy Area Muslim places For The Muslim On The World ,makkah And Madina. The capital Ofsaudi Arabia Is Riyadh It And The Population In About 5million [with/which has a...]. Dammam City Is an Important City For Saudi Arabia Because It Has Most Of the Oil and is Also Located Close To The Sea.