I want to study CISCO (networks ) to be certified?

but I don’t know how to start and what are the contents of this study , how long it will take and are there any requirements needed Actually I am 36 years old and I am working in Dubai and I have only a free time from 6PM every day and I am worry about if this study need a free long time a day . and I want to know where can I start in Dubai and how much it will cost