Where can I find IE in Windows 10?

You can use the search bar in the Start menu to find it, simply by entering internet explorer:

You can also search through the Start menu:

Go to the All Apps/All Programs list, scroll down towards the bottom and click on Windows Accessories:

Once you open that folder, you should see Internet Explorer:

You may want to right click IE from there and either pin to the Start Menu or the Taskbar so you can access it easier.