When you downloaded NVDA from http://www.nvda-project.org/wiki/Download please open the downloaded.exe file. Windows will ask you "do you really want to install this program on this computer?" please click "yes" to continue. In the next step you have to agree to the terms of the program. Please activate the checkbox "i accept" and go on with the tab-key. Now, you have three different possibilities to install the program:
1. "create a portable version", which is very useful if you want to take NVDA everywhere were you go and need it. The setup will create a copy of NVDA on a USB-Drive. That means, you can take the Hard-Drive with you and if you want to use another computer were is not any screen reader installed, put your USB-Drive in the USB- Port. When the drive is recognized by the computer, click on the "NVDA.exe" file and have fun to work with it! Maybe a person, which is able to see, should help you to click on the .exe file.
2. "still running NVDA" chose this, if you want to test the new version before finally installing or taking it on an USB-Drive. The setup assistent will close and the version is running from the downloaded .exe file! That means, you can test the version first, and if you don't like it, just close it and open your older installed version or your favourite screen reader! You can close the program by pressing NVDA key (it's the same like Jaws key) + the letter q. Please confirm the following dialogue with enter. The screen reader will close. You'll know that because when the program ends or starts, you'll hear a special sound.
3. "install on this computer" will install the program on your computer. After you click this, another setup assistant will open. Following its instructions and the installation will not take much time.
If you have NVDA allready installed on your computer, but want to take it with you on an usb drive, please go in the NVDA menu and click "tools." there you'll find a feature called "create a portable version" chose this and a dialogue will open were you can chose the drive were the version should be installed. This is another great possibility to take your screen reader with you and show all your people what a blind or disabled person can do with NVDA!