Very good! A few issues with subject-verb-object placement (like "grew up my mother" -> "my mother grew up") and some phrases, but that just needs practice :)

My childhood is strongly connected with Kazakhstan, I grew up there with my mother and now my grandparents live there. I visited this country annually for 22 years. My grandparents live in a small city that is called Stepnogorsk. This city was built in the second part of the 20th century for military purposes in time of the Cold War between the Soviet Union and the USA. A private factory is located in the rural area of this city where biological weapons were manufactured. Nowadays, that factory is closed, but there are some private companies in the buildings of the factory . All This city has immense value for me, the most of my childhood memories are related to this place. I enjoy every second that I spend there. I remember the path to the village, where I used to swim in the tank. I would take a lump of wood and attempt to make a ship (you probably meant "a stick") for fishing. I came up with the construction where one piece of a thread is embedded to the high part of the ship and it has a hook with a worm on the lowest part. I like that time, it would be great to visit that city every year.