Computer Audio for Dummies

I would like to get my feet wet in computer audio, but will admit my knowledge is very limited about it.
I have a MacBook Pro laptop. The rest of my system can be seen in my system page.
Here’s what I know I want to do right off the bat;

Build a library that I can pick and choose what to play- mostly for convenience & backround music. But if it is good enough, might become a source for serious listening.

Record music from some/ all of my other sources.

Download music.

I haven’t done anything yet other than purchase a stereo cable that allows me to hook one end to an unused input in my pre amp and the other to my headphone jack on my Mac.

Should I look into a DAC or somethingthing between the two for better sound quality?

Thanks in advance and please, easy on me as I know not too munch in the digital/ computer world.