Once, you have purchased extra IP(s) for your Windows VPS from your client-area, a technician analyst will route the IP(s) to your Windows VPS control panel for you to configure within your Windows VPS.
To proceed, you would simply need to follow these steps so the IP will be enabled within your Windows VPS.
1) Login to your Windows VPS control Panel.
2) Once logged in, click on "HyperV"
3) Click on Your VPS Name.
4) You are now at the page to administrate your Windows VPS. You would need to click on the "Network" tab.
5) Once, on the network administration page, you would need to click at the bottom on "Add IP"
6) You may now select "Randomly select IP addresses from the pool" and specify the number of IPs to be added. The IPs are preallocated to your account and the number of available IPs would depends on your Extra IPs upgrade. Then click on "Add"
7) Once back on the network administration page, you can instantly activate the IPs by click on Restore External IPs. And after a configuration change, the IPs will not be loaded and active within your Windows VPS.
If you would like to change your Windows VPS primary IP, you would need to follow this guide.