The Underground Railroad was a network of people that helped fugitive slaves get to the freeland (northern U.S. and Canada). It was not ran/maintained by one person or organization, instead it was made up of lots of individuals. Some of these people were white, but most were black. It effectively moved hundreds of slaves northward yearly (according to an estimate, 100,000 slaves were moved up north between the years 1810 and 1850). Though that seems to be a big number, still, lots of slaves were caught and killed for their actions, if not, they were brutally punished.
The way they went about escaping from their masters was using, of course, the Underground Railroad. Since the name of the "organization" was called the Underground Railroad, they also used terms associated with the railroads: "Stations/Depots", being where the fugitives went to rest and be provided with hospitality and money; the stations/depots were owned by the "Stationmaster"; "Stockholders" referred to the ones that contributed money or goods; The ones that helped the fugitives get from one station to the next were called "conductors". For a slave to escape, it proved to be a very tough obstacle. In some cases, a "Conductor" would go to the plantation disguised as a slave, and once inside, he/she would guide the soon to be runaways northward towards a "station". They would normally take on this task at night, and travel up to 10-20 miles upon reaching a station. The stations were normally marked by a lantern in the window, or sometimes the stationmaster would tug on his/her ear as a gesture to the slaves to follow him/her to a station. At the station they would be fed and allowed to rest, usually hiding in barns and other shelters of the sort.