DR Laura, you need to make a playlist of all the music you'd like to listen to on your walks.
When you have the itunes application open, you'll see all your songs you have imported in the list called "Music", under the "Library" column. It's the first thing at the top of the left on my computer.
Go under the "file" menu at the top of the computer screen when you're in itunes mode. When you pull down from "file", the first item should be "new playlist". Select that and an "untitled playlist" folder will appear under the playlist column. You can click on this folder and rename it if you want, say, to "Walking Music".
Then, click on whatever songs you want in your play list and once they are highlighted, drag them left into the playlist folder. Voila...you have your very own playlist.