With such a general question, you should probably start with a textbook in Epidemiology - The chapter on study design, the paragraph on case-control studies.

You should consult "PARK Text book of preventive and social medicine .

Thank u Dr Martin and Dr Ijaz

for general information

Its not difficult

just plan an objective and rationale of study

ERB approval 

inclusion and exclusion criteria

methods

determine sample size using formula calculation (Openepi or WHO) case control

determine statistical methods for depending what you want to determine

Co-relation

prediction

Risk assessment etc

but for this you need to study details of all mentioned points before

nice