How do I get to level 51?

The same way as you advanced to other levels.... I read instructions about how to play June’s Journey before ever starting to play the game. When the game first opens, close to the screen’s upper right corner, there’s a gear inside a small green circle. Tapping on it opens the menu for “Settings”. Under the “Basic” heading is a long green bar labeled “Help”. Tapping it opens a list of topics that provide fairly detailed (but not complicated) instructions and explanations about how to play the game. Anyone reading all that’s listed won’t have too many questions afterwards.