You have to press your A button to jump through a window when you are near it. You can only jump through two windows before you die so you will need some medical spray in your inventory. There are a couple of good perks you can get to help with this achievement these are Hypochondriac: which lets you start with a medical spray and Medic: you will get two uses from each Medical spray you find, including the one you start with. When you have jumped through your 99th window the achievement will unlock.