You installed manually, right? Just do as requested. The Install3.1.4 disk contains the requested library, so just insert it. And next time, please use the installer. Or at least, copy both workbench.library and icon.library from the Install3.1.4 disk to LIBS:, as follows:
copy df0:libs/workbench.library to LIBS: clone
copy df0:libs/icon.library to LIBS: clone
