Answer 1

Hazlo asi:

N = int(input())
for sum in range(N+1):
sum1 = 0
sum1 +=sum
#sum+=1
print(sum1)

Answer 2

I think this may do what you want:
N = int(input())
sum = 0
for add in range(1, N + 1):
sum+=add
print(sum)

And it would be nice if Sololearn could build google translate in this Q&A, that would be a pro feature i would like.