Listen to the song to identify the sample or break you wish to use. Play the song in your turntable until you hear the portion that will be the basis of your new DJ beat.
Record the sample. Use the digital sampling function if you are using a digital turntable interface such as Virtual DJ or Serrato Scratch. Otherwise, connect your turntable to your personal computer and record using an audio recorder utility or your audio editing software, such as Pro Tools or Logic. Push "Record" at the beginning of the sample. Push "Record" again to stop recording when the sample is complete.
Export the sample into your audio editing software if you had not already recorded it there. Select the "Import" option under the "File" tab on your audio editing software. Choose the sample from its saved location.
Play the sample in loop mode to preview it. Make sure it loops exactly and in appropriate timing. Delete small segments from the beginning or end of the sample as necessary until it loops as desired.
Open the multitrack viewer on your audio editing software if you are not already using it by default. Copy the sample and paste repeatedly in the multitrack timeline as desired until your DJ beat is the desired length.
Add drums, instrumentation and effects to the surrounding tracks in the multitrack viewer as desired if necessary.