If you've never owned a Vostok watch before, setting the time and date can be a little tricky. And the fact that the manual is in Russian doesn't make matters any easier.
One thing to keep in mind is that this watch has a screw-down winding cap with an internal rubber gasket. You always need to close that completely after winding and setting to keep it waterproof.
Also, there is a shortcut to setting the date quickly without having to turn through 24 hours to move the date ahead one day. Basically, you can move the hour hand between the 8 o'clock and 12 o'clock positions to advance the date.
Here is a link to the Vostok Amphibian manual with complete instructions on how to set the watch. The manual is in English.