To call in Skype, at first you need to create an account. To do this, visit the official website and create an account using the online form available. Once the account has been created, download and install the application and log in with your newly created account. If you recharge with credit, you will be able to call on landlines and mobiles. However, you also need a microphone to be able to speak. From the Skype interface, dial the numbers or use the Add button to add another user. When the user has been added, double click their name on the list and you'll initiate a call.