if you are probably trying to cal your friends out of skype, so you need skype credit to call outside. Just in case you add your friends(who are on skype too) to skype, you can call for free.
You can add contact following these steps:
In the menu bar, click Contacts
> Add a Contact
Enter the Email, Phone number, Full name or skype name(if you already know your friend's name on skype)
of the person you want to add. If the Skype account of the person you wish to add is displayed, click Add
below the contact.
If more than one Skype account matches your search:
for a list of matching Skype accounts and click Add contact
next to the one you wish to add. Before the contact can be added, you must send a contact request to that
person. Enter some text to introduce yourself and click Send request
. The contact will be added to your contact list, but will appear offline
until they accept your request. Once the person agrees to your request,
they will be added to your Contact list. Then you can make free calls and free video calls to that person.
Hope this helps,