I am assuming you using Windows 10. You can go to "Type here to search" and enter "cmd", then click on Command Prompt.
Here are other ways to open Command Prompt:
You open Command Prompt via the Command Prompt shortcut located in the Start menu or on the Apps screen, depending on your version of Windows.
Another way to access Command Prompt is via the cmd Run command or at its original location at C:\Windows\system32\cmd.exe, but using the shortcut is faster for most people.
You can read more about Command Prompt here: https://www.lifewire.com/command-prompt-2625840