My wish & my dream is to work on board ships, how to get a chance?

First of all, you must to know which Rank you want to work on Vessels Deck / Engine (officer, engineer, Ratings such as OS, AB, welder, cook, galy boy ....
etc).
All above ranks should have STCW95 certificates & Seaman Book but study for ratings is not a same for off/eng.
( tell me which rank u want apply & i will let u know all details).
Regarding how to get a chance in Maritime industry the same all industries but after you have the all documents forward your CV to maritime & agencies companies by internet & if you have in your city any agent or co.
working in this field dont hesitate to apply there and KNOW THAT everything in the first is difficult but not impossible.