learn to edit css & php?

[Graham35]

Hi.
I am trying to edit some templates for my shop site,

when I edit my php and css codes with notepad++ , things like tagline and other things I want to do away with, how much of the code should I remove, should I remove the whole line (or lines) if its relevant to just the tagline or do I leave some of the code in and just remove 'Tagline' from the abbreviations and leave the rest of the code. I am not sure how far to go in removing codes.......

Your help would be appreciate,

attached jpeg

PS...... where is the best website to learn a bit more about coding, css and php, which would be useful for me working on my shop site. ta