In your example, you're asking the user for a number and then you're setting total and nums equal to zero. This results in your first number being ignored by the program. I included the complete working code below:
num = int(input("Enter a number: "))
total = num
nums = 1
while (total <= 100):
num = int(input("Enter a number: "))
nums = nums + 1
total = total + num
print("Sum: "+str(total))
print("Numbers Entered: "+str(nums))
I hope this helps!