When you are trying to conceive, you need to know when you are fertile! The easiest first step is to calculate when you will likely ovulate. If you have a healthy luteal phase, that will be 14 days before your next period. The ovulation calculator on the website of webMD helps you calculate when your next most fertile days are so that you can fall pregnant.
The calculator gives you the approximate date of ovulation plus your likely fertile window.
This is because to make the most of your cycle you will want to start trying 4 days before expected ovulation as that is when your fertile window likely opens.
The best way to find out when you will be fertile, is to however chart your cycle. That way you can recognize when your personal fertile window opens and before you ovulate.
To learn how to chart, sign up to my free charting course.