Problem Upgrading Linux Lite 3.4

[bitsnpcs]

The question I was actually asking was where is it documented what PPAs I SHOULD BE USING.  i.e What are the current PPAs, and when a version goes from 3.4 to 3.6 or 3.8, how do the PPAs change?  Any insight on that?  I've had several linux installs go bad when the repos just decided to go away, and I had no idea what to do to replace them.

The staff/developers will know this answer, as to what is pre-installed in LL.
I have added softwares/changed so it is not useful if I check.