Your post is extremely cryptic and could be read various ways but I am going to assume you are asking about using music that is not provided by the program in an exported Photostory project. Is that correct?
If so, the answer depends entirely on the source of that music. You say your own music; depending on precisely what you mean by that the answer could be Yes or No!
If you mean music that you have composed and which does not use loops or samples created by any third-party (unless you own a full commercial licence for those loops), then yes, you can use that music. You automatically own the copyright to anything that is completely and entirely your own work.
If you mean music that you have saved to your computer from an external source, e.g., music ripped from a commercial CD, or from a YouTube video, or saved from a streaming service like Spotify, then the answer is most definitely No. To do so would be a very serious infringement of copyright and could, in the worst case, lead to you being sued.
As to how to add such music to your project, you would simply place the audio file, preferably in .wav format though .mp3 can also be used, into an empty track on the Timeline view of the app, at the place where you want that music to start.
I hope it goes without saying that you will almost certainly have to "adapt" the audio in some way in order to make it "fit", but initially at least you need to be sure that you understand and comply with copyright legislation with respect to adding music to your project.
Hello Jeff the music I hoped to use is songs purchased from I tunes, does this comply with copyright , legislation, as I have paid for them, or can you purchase from the store any form of popular music, as they are what I like to listen too.