Heya deysi,
so have you already been to the doctor for the pill, or are you just wondering?
Usually, when you pick up birth controll pills, there is an information leaflet inside the pack which should answer all those questions.
There are different types of pill, and different brands of types!
Usually though as a general rule, your protection depends on when you sart taking it- if you take your first ever pill on the first day of your period, you should be protected immediately. You can have sex whenever you like. If you take it mid-cycle, or any other time during your cycle, it can take 14 days, you'd be better off using condoms untill your next period.
There are lots of resources on the internet to answer common questions, but first try just typing the name of your own pill into a search engine- them you'll be sure the information is relevent to you.
The pill is nearly 100% effective in preventing pregnancy if taken correctly (they say 10% but I got pregnant with my first daughter while taking it-properly!)
it will not protect you against sexually transmitted infections or diseases though, condoms combined with the pill should give you complete cover.. Some sexually transmitted diseases can lead to infertility, ad most are unpleasant or painful, so it's important to remember to protect yourself.
Take care
xel.
