Please house,how can i update my Apple device.

These support pages should be helpful in describing the available procedures to update your iPad:

Update your iPhone, iPad or iPod touch – Apple Support

Update software on iOS and iPadOS devices in iTunes on PC - Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

You provide no details of your iPad or currently installed version of iOS/iPadOS. Your iPad can only be updated to the highest supported version - which for older models of iPad may be limited.

Here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:

iPad1 - iOS 5.1.1

iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi & Cellular)

iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi & Cellular)

iPad Air1, iPad mini2 and iPad mini3 - iOS 12.4.8

Newer models, not appearing in this list, are all able to be updated to the current version, iPadOS14.

I hope this information proves to be helpful to you.