if you want to hold a note out it sounds like you are talking about looping.
like you have a sample of 1 string note, but its short and you want it to play for as long as you hold down a pad/key... in a sampler thats a loop.
you are going to want to go into the trim mode and setup a loop on the sample.
very important! - once you get the loop you want you need to change the sample mode to "note-on" instead of "one-shot".
this should be in the program settings.
this is all covered in the manual under looping and note-on/one-shot.
as is mute groups and mute targets.
basically mute groups are a way to make a group (two or more) of samples cut each other off. only one sample out of the group can play at a time. if you have one of the samples in the group playing (you can still hear it) and you trigger another one it will cut the first one off so you can only hear the second one.
mute groups are useful for things like hi-hats were you can't have an open and close hat sound at the same exact moment on a real drumkit. the are useful for a lot more than that creatively, but they were originally designed for hi-hat "choking".
mute targets work similarly except you set 1 pad to cancel another pad, but not the other way around. if you spend much time messing with mute targets you should probably look into mute groups instead.
