How do you approach your professor if you do not understand or know how to do the homework at all?
To address the part of the question &quot;what do I tell the Professor&quot; to help with the problem &quot;I do not understand the lecture material&quot;:

Clear your head
Start reading your notes, word by word
As soon as you get confused (even a little bit), stop reading. On a piece of paper, write down what you are confused about, and why.
If you can, skip over the confusing part and continue with step 2. If you have hit a brick wall and can't understand anything that follows, stop.

Take your piece of paper to the office hour and work through it with the Professor. This will give you both a better idea of precisely what you are confused about, and how to resolve it.
Hopefully, when confusion about the lecture material is resolved, the homework will start to make sense.