Hi Gabriele,

Messenger service has been stopped by Microsoft long away and Skype has replaced it.

Starting from 8 April 2013, Messenger users, previously Windows Live Messenger/MSN Messenger, will  not be able to use the service.

Messenger users can transfer their Hotmail and Outlook.com contacts by signing into Skype with their Messenger ID.

With Skype, you can share a story, celebrate a birthday, learn a language, hold a meeting, work with colleagues – just about anything you need to do together every day. You can use Skype on whatever works best for you - on your phone or computer or a TV with Skype on it. It is free to start using Skype - to speak, see and instant message other people on Skype for example. You can even try out group video, with the latest version of Skype.

Upgrading to Skype can help you communicate in flexible ways, and be connected on more devices and platforms including Windows, Mac, iOS, Windows Phone, Android and soon Blackberry.

Skype offers many features Messenger users know and love such as emoticons, group instant messaging, and screen sharing, and we think you will discover many other advantages of using Skype:

• Instant message conversation history
• The ability to edit and remove instant messages
• Being able to share files and contact information
• Video calling and instant messaging with Facebook friends
• Group video calling

You can follow the below steps to get Skype installed:

1. Firstly you need to make sure you have Skype installed, which you can download from the link here. 
2. If you already have Skype installed, make sure you have the latest version by going to ‘Help’ then ‘Check for Updates’. Next, open Skype; if it automatically logs you in then log out (‘Skype’ then ‘Sign Out’).
3. Then, you need to select ‘Microsoft Account’ from the right hand side, which is the account you use for Messenger. After logging into your Microsoft Account you will be given two options.
4. If you do not already have a Skype account simply click the ‘I’m new to Skype’ button to convert your Messenger account into a Skype account. If you already have a Skype account then you have two options available to you. The option on the left, labelled ‘I have a Skype account’ will merge your existing Skype account with your existing Messenger account. The alternative is to convert your Messenger account into a separate Skype account by clicking the ‘I’m new to Skype’ button.
5. After you have either merged or upgraded your Microsoft Messenger account you will be able to use Skype to communicate with all your contacts, regardless of whether they are still on Messenger or have upgraded to Skype.

I hope this helps.

Regards,
Lokesh