You need to be aware that gustar does not work like the English "to like", but rather backwards. The thing that you like is the subject and thus determines the conjugation of the verb, and the person who is liking will be the object.
- Me gusta ese chico. - I like that boy.
- Nos gusta ese chico. - We like that boy.
- Les gusta ese chico. - They like that boy.
- Me gustan esos chicos. - I like those boys.
- Nos gustan esos chicos. - We like those boys.
- Les gustan esos chicos. - They like those boys.
Actually, it would be I like that tall boy. We know this because the word chico, with an O, is used. The O indicates it is masculine. This is also seen in the verb alto, and ese (masculine). If it was I like that tall girl, the sentence would have been "Me gusta esa chica alta." Hope this helps :)