Try right-clicking the F@H system tray icon and choosing advanced view. At the moment there can be several hours of delay as your client waits to be issued a work project.
This is due to the enormous surge in new clients requesting projects and the F@H project server struggling to cope with issuing workloads to them all. You may have to wait a little while but of the client is running on your pc and is on the firewall exceptions it should pick up work in time.