You need to apply for a course in a university/ college. After receving the CAS letter ie Confirmation of Acceptance for Studies, you need to apply for Visa under Tier 4 General Student Category.
Find below the links for the guidlines:
http://www.ukba.homeoffice.gov.uk/studyingintheuk/adult-students/

Here I have listed the link which tells you about the process and procedure for getting a Student Visa of UK.

http://www.impeloverseas.com/StudyAbroad/UK/UK-Visa-Guidelines.aspx

I have listed the link below for you where you can get all the information regarding the process of getting a UK Student Visa.

http://www.ukba.homeoffice.gov.uk/visas-immigration/studying/adult-students/apply-outside-uk/

I think you should visit this link which i have listed below and you will get all the information about the process and procedure of UK Student Visa-

http://www.educationuk.org/Article/Applying-for-a-student-visa

Below is the link of the website where you can get all the information you needed about the process and procedure of UK Student Visa-

http://www.infozee.com/uk/visa.htm