Muon and Kubuntu Package Management

[M.R.P. zensky]

Hello I am somewhat new to linux Kubuntu. I am wanting access to FSF GNU software can anyone give me suggestions for how to access this software. Is the trisquel repo best for this?. Also their is a graphical package called Muon on kubuntu.It slows me to add repositories but says to enter the complete APT line on the repo that you want to add. What does this mean? Do I just type apt etc.etc. or sudo apt? Can anyone tell me what the best repos are for linux? Or the best software cd rooms?
	also in ubuntu in the graphical interface I select discover and then at the bottom of the screen I can select sources. When I do this at the top of the screen it says snap than bellow that UBUNTU Default below that their are a number of check boxes but half are not checked. What is this?