Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
If you like to introduce yourself, to the community, go here:
http://lmms.io/forum/viewtopic.php?f=4&t=4480
-Its all about selecting the part of the sample. You need to have no volume in both attack and release point.
Take a look at the picture
All purple-points represent a safe point to both start and terminate playing the waveform. The blue rectangle represent ONE such selected part of the waveform, but any selection with a purple start-pos. and a purple end-pos. would result in click-free output.
So you need to make both start-point and end-point in that way.
Magnify the spectrum and place both start and end on the horizontal 0-output-line
I go through AFP uage in this: