Can anyone please demonstrate or advice me how can I receive or give a debt in OpenERP or how can I rent an office? I know that there is no such a module to manage loand and this kind of instruments but is any other way?
For renting an office you could create a service type product code 'rental' and then create an invoice. Then set up a recurring transaction to create the invoice each period.
Receive or give a debt - if you need a document, then process an invoice, otherwise a journal into the GL