To know if you have Windows 10 on your computer, you can follow these simple steps:

1. Click on the Start button or press the Windows key on your keyboard.
2. Type "winver" in the search box and press Enter. This will open an "About Windows" dialog box showing the version of Windows you are running.
3. Alternatively, you can go to Start > Settings > System > About. Here, under "Windows Specifications," you will see the Edition (such as Windows 10 Home or Windows 10 Pro) and the Version number.
4. Also, from the Settings app, under About, you can find information about your system including whether it's 32-bit or 64-bit.

If the edition says Windows 10 (like Windows 10 Home or Windows 10 Pro), then you have Windows 10 installed on your device.