Assuming you mean dialogue here, rather than sung vocals. Which modules did you try?
With regard to tutorials, yes they can help and we could have more of them, but you might be better off posting short descriptions of specific examples of the processing you are trying to do with SL, including also uploading a short zipped extract of the problem audio. There’s a lot of expertise in this forum and others may well be able to point you in the right direction - but only if they can actually hear the audio you are referring to.
For example, try uploading short extracts of the guitar and keyboards which ended up in the same layer, and the spoken voice(s) from the business meeting.