Install explanation, and dependencies

I think that install explanation and how works, may be more detailed ...

Maybe you are right. I'll try.

-It seems that also requires address module installed....
I don't use the address module, because I really don't ship my products. Any idea about what can I do ?

You should use address module anyway because you will need to do an invoice and depending on invoice's address the system will determine, with the help of the region module, whether it will need to apply any tax at all.

I have to define a region ? Only a default region or also a shipping region or what?

Any, really. Deafult is fine.

And then create a new vocabulary, with its terms that are percentage value of tax
I assign this vocabulary to my products
That's all ?

yep. Then you will need to set a tax term to each product during product creation.

When I view the tax applied in orders ?

At the last screen during checkout

Remember to set your settings for this module on admin/ecsettings/tax_by_taxo. You set here the region and vocabulary to be used.

I applied this to the last dev version