Accept that all your memory will be erased, like pictures, and songs. This really stinks, and there is no way to get around this.
Shut down your computer/Macbook. Press and hold the “power button” until the screen goes black.Start up your computer and insert disk one, before the start-up chime.After the disk loads, the stubborn box will pop up again, so shut down your computer. The disk is now in your computer.Now, start up your computer, again, and before, or right as you hear the “start up chime” Press and HOLD the pound-like key (command key) next to the space bar. If that doesn’t work, try the “Alt” or the “Ctrl” keys. Every keyboard has those keys.Continue to hold the key, and a box should pop up, saying “what to use to start up your computer”.Select the disk as an option.Click around for a little until you find the right options. Click the install button, and the mac software will be installed.