Well you can move things like photos, videos, music, etc. (not apps) to the card and that would free up space. Some phones come with a file manager app, but if yours doesn't, you can download and install one. Then using that (a file or two at a time) you can move the files over to the card.
You can also move them via a connection to a computer via USB cord (faster and easier method). Just connect the phone (with the card in it) to a computer and move all the files you want over to a folder or folders on the computer. Then once that is done, using the same USB connection, move or copy the files over to the SD card. I suggest copying rather than moving. Then you have a backup of them all on the computer.
Be sure that you also access any...