You can use Windows Media Player to do all of it.
For the CDs you already own, you will "rip" it to the computer. When WMP starts playing the CD, open up the full program by click on the icon at top right with the 3 boxes and left facing arrow. Then click "Rip CD" to start uploading the CD contents onto the computer.
For music on the internet, you'll need to download them to the computer. Technically, you are not supposed to download music posted to YouTube, etc. for copyright issues. There are free programs that will do it. You can purchase music from iTunes, Amazon, etc. and legally download them. Prices usually run $0.99 per song. Follow the instructions from wherever you purchase them or whatever software you use to download from websites.
Once the music is on your computer, you can burn your CDs. The easiest way is to create a playlist of your favorite music in WMP. Keep the final size of each playlist to within a CD's max capacity. Once you have your playlist(s) to your liking, click on "Burn" and drag one playlist name over to the "drag list here to create a burn list" - all the music from that playlist will be listed there. Then click "Start Burn". Let the program complete the process and eject the CD. Then you can burn your next playlist.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)