You can also find it on your Kindle under settings, your account. The last entry is your send-to-Kindle email.
And be sure you understand that this is *NOT* the address of your Amazon account, though some people do refer to something called a "kindle account" (and it's not clear what they even think they mean by that).
The kindle address is device-specific, so if you have more than one device you'll have more than one "kindle address" -- but it's still just the one *Amazon* account.
You use the same Amazon account to buy books & so on. You use the Kindle address to send things to a device.