Hello Royal!

I just got there... installing the shipping... and I am new with this. Can you please help me with the settings?
I am using 1.3.7 version.
I didn't install yet the module, but my situation is like this:
My products are just good to be sent by lettermail, so, this one would be the be4st option... but: how do I set up the shipping module so the rates to change at a certain number of products [because of the weight] ?

I have here the logical idea... but I don't know how to set it up:
DEMO:
CANADA US INTERNATIONAL
<30g max 10pieces - 0.52 - 0.96 - 1.60
>30-100g max 20pieces - 0.96 - 1.15 - 2.30
100-200g max 40pieces - 1.92 - 3.20 - 6.40
200-500g max 80pieces - 2.65 - 6.40 -12.80

Should I put the rates and set up the weight of my products, so when they hit a certain total weight for the rates to jump to the next level? I ma just thinking because I don't know how it's working.

Thank you!