I am using Web Page Maker V2; in wich parte must I paste the code to see the form into my page ?

On the Form Builder:
1. Open "Setup & Share" tab on toolbar,
2. Click on "Share Form"
3. Copy the code provided at "Paste this code on your web site".

On the Web Page Maker:
4. Click on "Insert" on the main menu
5. Select "Html code or Script code..."
6. Paste the code you got on step (3) above

You should see the form when you publish the page to your web site.