Adding new admin tools to dashboard

Hi,

I have little experince with wordpress plugins and widgets and can;t seem to figure out how to add an app that i wrote in php to my new wordpress site. This app allows me to add each book in my collection to the database. You can add a book, edit, see all, delete and each book has a name, author, etc. I have written this in php and it works without wordpress.

I want to add it to wordpress. When I log into my site I want to be able to see it under my dashboard. For example, above “Posts” there should be “Books” (sub menu “Add New”, “Edit”, etc.) and when I click on the submenu links the code that I already wrote should show up to the right.

Also, I guess I will need a widget or something to actually show the books on my site but I will worry about that later.

I don’t know how to convert my code into a plugin/widget.

Does anyone have any idea on how to do this or can point me in the right direction?

Thanks