Launch Fruity Loops. Click "Channels," and "Add One." Click on an instrument to open it in a new channel.
Right-click the instrument's name. Click "Piano Roll" to open the note editor. Click to enter the notes that you want the instrument to play into the piano roll.
Click the "Slide" icon, which is located directly beneath the wrench icon in the top-left corner of the piano roll. Click inside the piano roll to enter the notes to which you want the previously entered notes to slide. For example, if you want to slide a previously entered "B" down to "D," click inside the "D" space below the "B."
Click and drag the end of the slide note to adjust the length of the slide. Click "Play" to listen to the notes.