The Cleveland Browns have not appeared in a Super Bowl. They
did, however, play in 10 consecutive league championship games from
1946 through 1955. During that stretch, they won four titles as a
member of the All-America Football Conference from 1946 through
1949, and three as a member of the NFL (1950, 1954, 1955). They
would go on to win one more NFL title in 1964, two years before the
Super Bowl began.
"Browns", "Superbowl", and "win" are words that cannot be used in a sentence except negatively.
The Browns have never even been in a Superbowl, let alone won one.