for and while loops

[kydavis77 at gmail.com]

i was wondering if anyone could point me to some good reading about the
for and while loops

i am trying to write some programs
"Exercise 1

Write a program that continually reads in numbers from the user and
adds them together until the sum reaches 100. Write another program
that reads 100 numbers from the user and prints out the sum. "

but im not quite grasping those functions..

please bear im mind i am an extreme newbie at this...thanks in advance