If you do not have an external keyboard or cannot access the USB ports in the back of the unit, you can use the Windows On-Screen Keyboard.
To open the On-Screen Keyboard in Windows 7:
On Windows 7, you can open the on-screen keyboard by clicking the Start button, selecting “All Programs,” and navigating to Accessories > Ease of Access > On-Screen Keyboard.
To open the On-Screen Keyboard in Windows 10:
Go to Start , then select Settings > Ease of Access > Keyboard, and turn on the toggle under Use the On-Screen Keyboard. A keyboard that can be used to move around the screen and enter text will appear on the screen. The keyboard will remain on the screen until you close it.
You can set the OSK to open on startup, Select the Start button, then select Settings > Apps > Startup.