Please go to Skype.com and click "Download Skype".
You will be redirected to another page where you can select the needed Skype version. You can choose Skype for Windows or Skype for Mac. Then, click on "Get Skype for Windows" button.
Once the program is downloaded, please click on it in order to open it.
You will be asked if you allow Skype to make changes to the Device and you will need to click "Yes".
Enter your credentials and you are good to go!