To built a ship you must design it based on what it will be used for. For example, the inside of a passenger ship and a tanker are completely different.
Using various new technology, safer and more comfortable ships are built.

After the design is done, large, thick steel plates are cut based on the design. Shipbuilding is a dangerous work. They use gas to melt and cut the steel, so sparks fly all over. It also requires operations in high places and transport of heavy loads of steel. People at shipbuilding plants protect themselves with safety lines, helmets and steel-tipped safety shoes.

After cutting steel sheets, they put them together and make huge boxes. As these boxes are assembled, it’s started to look like a ship. Each piece is very heavy, so cranes are used for the assembling.
They weld steels to assemble, in other words, they melt steels and put them together. The melted parts become like adhesive.