If you have more than 10 products, you will find bulk upload very useful.
You probably noticed little yellow triangles like this:
It means that you need to enter Manufacturing/Purchase costs and Shipping costs, for you to see the real profits for each sale.
You can enter it:
Manually in Settings->Products - One by One,
Or you can use a bulk upload option.
If you do it manually, it will look like this:
For bulk upload, you may want to first download a spreadsheet with all your asins in it.
Then, after entering your costs into in, upload it via this page.