How could I determine a womans' fertility/infertility?

I do not quite understand the process and such.

A WOMAN CAN GET PREGNANT AT ANY TIME DURING HER MENSTRUAL CYCLE! This includes not just the time around ovulation, but also during her actual period. If the sperm do not come into contact with air, they can live within the female vagina for up to seven days! Ovulation DOES NOT happen at exactly the same time every month for every woman!

A cycle starts on "Day 1". This is the first day of the woman's period. The period can last for anywhere from three days to ten days, but the average is about six or seven, and shorter for women on the Pill. Normally, the woman's body releases an egg around Day 14, but it is different for every woman. Women cannot see or feel when the egg is released. This is called ovulation. Because sperm can remain alive in the woman's body, she is most likely to get pregnant in time period starting five days before ovulation and ending two days after ovulation. Again, there is no sure-fire way to determine which day ovulation is actually place on. If the egg isn't fertilized by sperm, eventually it will dissolve or be expelled from the vagina. This will tell the body that it should begin its next period, approximately (but not exactly) twenty-eight days after the beginning of the previous cycle.