To set the time, the crown should be pulled out gently and turned to set the hands to the correct hour and minute.
Keep in mind that water-resistant timepieces are a 20th century phenomenon. The Rolex Oyster being the first truly water-resistant watch, was introduced in 1927. Water resistant does not mean water-proof and most timepieces have a level of water pressure they can handle. Be sure to consult with your jewelry professional to understand these boundaries.
It’s a good idea to have your vintage timepiece cleaned every two years. If you notice your watch is gaining or losing more than a few minutes over the course of 24 hours, it’s time for a check-up.