请问怎样用subtitile的file (sub) ??

alantct

i hv a movie file, Lelio.Po.Po.2010.DVDRip.XviD.ONiE and another two files (seprate) is the sub  & idx file. may i know how to use or combine the video file so that i can watch it with subtitle ?  
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/ w9 o. d. M! vtvb now,tvbnow,bttvbthanks in advance.