Having Files on HDD when using SSD

I have attached an external SSD to my iMac late 2012 and put OS X El Capitan onto it and have it all working with the applications on it too. I can't seem to access my Documents and music which are on the HDD in the iMac as they don't show up in the Document's and Music folders in Finer. I want to keep them on the HDD any idea how I would go about doing this?