Cool, I'm being referenced!
After you do what Rolli59 linked, you still have to set up your OS to store documents on the HDD. Create a directory with a name like Daves_Documents, create subfolders My Documents, My Pictures, and so forth.
Then right-click on the system's My Documents and change the storage location to the one you just created on the HDD. Ditto My Everything Else.
If you have apps that store things other than in the My Documents tree, you will have to configure them individually to store to directories on the HDD. Used to have to do this with iTunes. There are a lot of better guides to using the SSD for OS f and the HDD for storage, but I don't have a handy link. Poke around.