First, use must produce some samples to sequence. Open the "Sample Picker" and "Buffer Manager" and select some .WAV files somewhere. Select one of them in the buffer manager.
Then, clicking on the sequencer's background area should yield a circle. If you press the Play button you should hear that sample play repetitively.
You may select different samples in the buffer manager.
To move a sample, drag it with the mouse.
To delete a sample, right-click on it.
To move a bunch of samples, select them with the middle-button, then they all drag as a unit. You can use shift to copy.
By default, the vertical axis represents volume. By pressing the By Resample Rate button, the vertical axis will represent the frequency (that is, pitch). In this mode you can compose limited melodies.
You may enter a filename in the entry box between the Save and Load buttons. Then when you press the Save button the sequence will be saved to that file.
A playing sequence can be altered by tapping in time on a gui button, a keyboard key, or a MIDI keyboard. In the first two cases, the pitch and volume of the new samples will be the current default pitch and volume. In the last case, the pitch and volume will be determined by the MIDI input (i.e., which key was pressed and how hard.) MIDI input must be enabled and the correct channel selected for this to work.