In the picture, the people are roasting marshmallows the heat from the fire is roasting the marshmallows which heats the stick. The heat from the stick transfers to the persons hand with direct contact which is conduction. Conduction is the transfer of heat through direct contact.
In the picture, the hot air from the cup is rising into the air. This creates convection currents, where hot air rises and colder air goes below the hot air. The heat from air/steam from the tea cup transfers to the air.Convection is the transfer of heat through gas or liquid.
In the picture, the sun's heat is transferring to the Earth. Radiation is the transfer to heat through air/electromagnetic waves. The sun and Earth are far apart but the suns heat is transferring to the earth through electromagnetic waves shown by the lines.