The problem is in the import line. You are importing a module, not a class. Assuming your file is named other_file.py (unlike java, again, there is no such rule as "one class, one file"):
from other_file import findTheRange
if your file is named findTheRange too, following java's convenions, then you should write
from findTheRange import findTheRange
you can also import it just like you did with random:
import findTheRange
operator = findTheRange.findTheRange()
Some other comments:
a) @Daniel Roseman is right. You do not need classes here at all. Python encourages procedural programming (when it fits, of course)
b) You can build the list directly:
randomList = [random.randint(0, 100) for i in range(5)]
c) You can call methods in the same way you do in java:
largestInList = operator.findLargest(randomList)
smallestInList = operator.findSmallest(randomList)
d) You can use built in function, and the huge python library:
largestInList = max(randomList)
smallestInList = min(randomList)
e) If you still want to use a class, and you don't need self, you can use @staticmethod:
class findTheRange():
@staticmethod
def findLargest(_list):
#stuff...