Although contar and 'to tell' are used very similarly, in English we say 'to tell sb about sth', where 'sb' is the direct object and the thing being told is introduced by the preposition 'about'. This construction is not the norm in Spanish, where the direct object is always the thing being told. [See also contar con]
-Me contó la historia — He told me the story /the story to me [Same]
-Háblame de tu familia / Cuéntame cosas/algo de tu familia — Tell me about your family [Cuéntame sobre/de tu familia??; not natural in Spanish (in Spain), although seen in bad translations and in Latin America]
-Me contó una vez que le robaron — He told me about a time was robbed (or He told me once we was robbed)
-Le conté lo del dinero — I told him about the money [Le conté sobre el dinero??; sounds unnatural]
-Ya te (lo) contaré — I'll tell you (about it) later [A menudo se omite el complemento directo de cosa - véase ya te cuento]
