Run the installation program. Wait until it initializes.

When you will be presented with a "Welcome" window, click "Next" button to continue. Follow instructions on the screen to select a folder to place the software, program group to create a shortcut to GemCalc, etc.

At the end of the installation process you may be prompted to restart your computer to update system files. You can answer "Restart later", but in this case GemCalc will run correctly only after the system is restarted next time.