just something small

[arvivlx]

oniisan wa shigoto (?)

i want to write that my brother is working as bartender in a restaurant near sea shore.

[vkladchik]

Ani wa umibe (no hoteru/resutoran) de baaten no shigoto wo shiteiru.

"Oniisan" is a word you use when talking to people in your family. "Ani" is what you use when talking to people outside your family. I'm guessing everyone in your family already knows where your brother words, so the sentence is directed at someone not in your family.