I believe you are making a common mistake - confusing the terminology of Odoo.
(I made this mistake myself when I first started playing with Odoo).
A 'company' generally means a set of partners (leads, customers, suppliers and employees), users (logins) and stock of products with a separately managed set of accounts.
An example of companies would be Odoo S.A, Odoo USA, Odoo Asia/Pacific.
A 'customer' is a partner that purchases products from a company.
Unless you need a separate company for separate physical or legal entities (like worldwide companies under a global holding company, or separately managed franchises reporting to a franchisor) - then you should not be creating Companies - you should be creating Customers. (I doubt you really mean to create companies in the sense that Odoo models them).
The best way to understand what you need to import is to manually create a single record and export it. That way you can see how the data you enter and the options you select get mapped into the fields in a CSV file.
Enter a Customer, you will see it does not show up as a Company, [even though you can check 'Is a Company' - which means only that the Customer is a business rather than a person - but not a 'company' as explained above].
You have created companies instead of customers, but since all of these are still 'partners' they will ALSO show up as Customers for your admin user (who can see all companies) but not your other users (who are generally restricted to a single company, unless you set them up to view more than one - even if they have admin permissions).
Take a step back, read some of the documentation, and try again.
Companies - http://doc.openerp.com/v6.1/book/multi/Logistic/config/config_company.html
Partners - http://doc.openerp.com/v6.1/book/2/3_CRM_Contacts/contacts.html