Thank you for your question.
If you are generally fit and healthy with normal weight and blood pressure, no major medical problems etc the oral contraceptive pill is safe to take. It is usually available only on prescription to ensure you are seeing a doctor for regular review.
The pill needs to be taken everyday irrespective of whether you have sex or not. Often the packet contains tablets for 21 days. You need a break for 7 days when you get a bleed. Your doctor will review how you are doing before you take the next packet. If all is well you can continue from the next cycle.
It is a highly effective reversible contraceptive (over99% effective at preventing an unwanted pregnancy) with very few side effects. Common side effects that settle are headaches, nausea, breast tenderness, but if the headaches persist you need to stop the pill and see your doctor.
There is a lot of good quality information on the following websites that you will find helpful. There's a lot of information to give that's not possible here.