The emulator works in window on the desktop and in fullscreen. During the emulation use the following keys:
F1 - Insert Disk in drive A. F2 - Insert Disk in drive B. F3 - Insert Tape. F4 - Insert Cartridge. F5 - Load Snapshot. F6 - Save Snapshot. Help - switch keyboard. F8 - switch to double size - only possible in windowed mode, F9 - switch fullscreen on and off. F10 - reset CPC Ctrl+F10 - Quit emulator. LShift+F10 - switch CPC model. + on the Numeric keyboard - increase frameskip (max 5). - on the numeric keyboard - decrease frameskip (min 0). Ctrl+F1,F2,F3,F4 - eject Disk A/Disk B/tape/cartridge.
you have to know how to use the locomotive basic on the CPC ie: cat run"nameoftheprog
I didn't tried cartridge by myself in Arnold but i presume you start the emulator, F4 to insert a cartridge, F10 to reset the CPC if the game does'nt start immediatly.