You will not find much information on this forum about getting a UK visa because most of the people on here are trying to go to Canada but what you should do is start by contacting the British embassy where you live. You will apply for your visit visa there. The most important criteria to getting a visit visa to anywhere is showing that you will return to your homeland after your visit.
You can find the British embassy according to where you live here:
http://www.fco.gov.uk/en/travel-and-living-abroad/find-an-embassy/