Are you looking for code?
(This is in python, but easy to adapt for other languages)
Python:
def sum_below_zero():
total = 0
temp_val = 0
for i in range(10):
temp_val = int(input("Input a number: "))
if temp_val < 0:
total += temp_val
return total
We tend to frown on people asking homework questions here. You're meant to be learning something, and handing you the solution on a platter is effectively cheating.
Paste some code you've tried. Explain what language you're using.