For RAMPS
HEATER_0_PIN is D10
HEATER_1_PIN is D8 since 1 is always bed
HEATER_2_PIN is D9 but FAN is is also 9, so make sure to have fan not enabled or set to a different pin if you have a extension board.
In Host make sure you have not only set a temperature but also enabled heater (flat button left of slider). If it is crossed it is not enabled.
Also check log if firmware did go into dry run mode for some errors like not connected bed etc.