Hello @MickeyK36 ,
I took a look at your account and was not able to see any documents added to the Library, just images. If you are linking to a document (i.e. Word Document, PowerPoint, Excel, etc.) It will open that program on your computer. If you are using a PDF file, then this will open in either a browser window or in a PDF Reader.
What type of file had you uploaded to your account? How did you want the file to appear when your contacts opened it? (i.e. did you want it to be editable or not).
At this time you cannot add an attachment to your emails sent from Constant Contact but you could include a link to a document in your email if that is what you were looking to attach. Can you take a look a this FAQ for more information?