Deleting songs off of my iTunes library?

I checked all of the songs that I DONT want and then I clicked shift delete and the message " are you sure you want to remove the selected songs from the list" came up. Now does this mean it will delete only the ones I checked or it will delete all of the songs in my library. Srry if this is rlly dumb but I rly do not want to screw up anything cause the last time I did I had a major meltdown and my family couldn't stop me from crying and freaking out. I know, sad right? :p anyway thank u! 10 points for anyone who rlly helps me and gives me a serious answer :)