Question: how to use itx train?
Answer: Step 1: Buy the ITX Tickets Online. ... 
Step 2: Take the Metro to Yongsan Station. ... 
Step 3: From Yongsan Station, Take the ITX Train to Gapyeong Station (60 minutes) ... 
Step 4: From Gapyeong Station, go to Nami Island Stop (5 min).