How to use the If function in excel?

So I have a question. If I have data as follows:

a / b / c / d

aaa / 123456 / $100.00/

aaa / 123456 / $100.00/

aaa / 123456 / $100.00/

aaa / Total / $300.00/

bbb / 221454 / $10.00/

bbb / 221454 / $10.00/

bbb / 221454 / $10.00/

How do I make an "If" function to create a text on line D as follows: If subtotal is less than $100.00. Then write (No) on Line D next to every Serial Number line. Not only the subtotal, but next to every serila number under that subtotal.

---OR---

How do I make an if function to make all serials above subtotals under $100.00 to be automatically hidden so that I can manually write (text) next to the ones that need it or not.

The first option would help me but the second one is another way of doing it in case you don't know how. Anyway, thanks! I dont think the first option is that complex, I just need a how to... Thanks!