Sampling a track requires 90% creativity and 10% of the effort. In general terms, sampling music is a process of taking a portion of a song and processing it through a DAW to create new music. You can reverse the clip on the DAW, increase the pitch, loop it up, or use it in a completely new way. You can also assign slices of sounds from your sample to use on your MIDI controller as a completely new element. There is no one way of sampling a sound. As long as you save yourself from the copyright issues, you can use any track and create whole new music and adding a touch of the sample to make it interesting.