For sperms to get to the Fallopian tube, sexual intercourse must take place. The man's penis becomes stiff so that he can insert it into the woman's vagina. The climax of sexual inter-course occurs when semen, a sticky fluid containing sperms, is ejaculated into the vagina. The release of semen is a pleasurable feeling called an orgasm. The sperms swim into the womb and up the Fallopian tubes.
Fertilization occurs if the sperms meet an egg.
Although hundreds of millions of sperms are released in an ejaculation, only one is required to fertilize an egg. After fertilization, the egg divides into a ball of cells and passes into the womb, where it continues to develop into a baby.