If you ask yourself "how do you get pregnant", the following will offer you some useful explanantions.
If a woman wants to get pregnant, male sperms have to fertilize the female egg cell. With a regular cyclus of 28 days, the ovulation takes place on the 14th day after the first day of the last period. In order to find out the exact moment, the woman can anally or orally measure her body core temperature every morning before she gets up and after a minimum sleeping phase of 6 hours. All the values are then incorporated into a diagram. Before the ovulation, the temperature normally is between 36,5°C - 36,8°C. As soon as the ovulation has happened, the temperature raises up to between 37,0°C - 37,3°C.
The egg cell normally can be fertilized over a period of 12 to max. 24 hours. The male sperms do have a life expectancy of 2-3 days (sometimes up to 5 days). Therefore, the best moment for having sexual intercourse is about 1-2 days before the ovulation takes place. Thus, the sperms can already reach the tubes. Here, they meet the egg cell, as soons as it has left the ovary.
If a sperm has entered the egg shell, this changes so that no more sperms can enter and the first cell division starts.
The actual fertilization takes place in the tube. From here, the fertilized egg wanders into the direction of the uterus where it arrives in a multicellular stage after approx. 4 days. Here, the embryo nests in by sticking to the uterus membrane over a wide area. So-called villuses slowly start to grow into the direction of the maternal blood vessels of the uterus membrane. Approx. 10-11 days after the fertilization, these are open, and the nutrition of the embryo via the maternal blood starts.