Firstly, yes there are copyright issues.
Now that we've got that out of the way...
When you say that you have scanned the book, do you mean you scanned it onto another sheet (ie copied it) or scanned it onto your PC? If you use a modern printer/scanner, most come with a suite of software that allows you to scan pictures to jpeg files and documents to pdf files.
PDF stands for Portable Document Format. It is an Adobe system that compresses the file to quite small sizes by disallowing any editing etc. To edit a pdf file you need Adobe Acrobat software which is neither cheap nor very user friendly. Anyone can read a pdf file by downloading the free Acrobat Reader software from Adobe.
So, if you have scanned the book to a pdf file, it will be on your PC (probably in your "My Scans" folder - depends on your operating system)