In the longer term you should always get the installation CDs when you buy a computer and keep them safe. I'm surprised that you didn't get them with a Lenovo, as that's quite an up-market computer. The real problem isn't Windows itself, though it is a problem if you don't have it or have access to a copy, but the device drivers. Without them aspects of your computer won't work, and it can be a very lengthy process on-line finding them. Assuming you can get on-line in the first place, as often some of the missing drivers are those that drive the internet connection.
Oh, and I AM in Belize.