Accessing to vps?
If you are running windows search for Remote Desktop Connection
Fromt hat app you just enter in your VPS IP address / username and then password when it asks.
Then go about installing like any other retro.
Some VPS providers disable remote desktop at first, or you need to install the OS first using VPN (this can usually be found within the client area, or in your service creation email).
If you mean you're stuck with where to purchase them, search online for providers. Choose the one that best suits your needs.