So, instead of making a new character, say a drawing of a telephone for "telephone", they combine two characters "electric" and "speech", each made themselves by combining older pictographs. "Electric": composed of "rain" (phonetic - sounds like the word "rain"), a symbol of a cloud with rain falling from it and "lightning" (semantic), a bolt of lightning; and "speech": a representation of words emerging from a mouth.

The "ideographic" part is for instance the symbol for "up", a line above another, or as we use, an arrow (itself a pictograph of a spear) pointing upwards.