How do I install Windows 10 from USB?

I have got myself a new latop Lenovo G5080, It comes with FreeDos and does not have any OS.

I am trying to create Windows 10 bootable usb so I can but it says I need Windows 10 ISO for it.

Where can I find Windows 10 ISO?

Microsoft has reportedly taken down the official download site for the moment.

Download Windows 10 Insider Preview ISO File - Windows 10 Forums

I believe that they never made the .iso for the latest build (10240) available, so far. That's the best build to have. It may even be identical to what is distributed beginning 29 July, although there has been no official word from MS on that.

It's probably available on unofficial sites or bit torrent. Links to such are not permitted here. If you have any proficiency with a search engine, it should be easy to find. Observe the usual cautions about downloading copies with pre-installed malware. 10240 may have been out long enough that the criminals are fully engaged.

I'm not sure whether you'd be able to activate 10240 without ever having an OS that qualifies for the update (Win 7, Win 8) installed and activated. I've read a variety of claims, but I they can be wildly inconsistent. You can do a lot with the OS without activating it, but I don't know for how long it'll run before it stops.

I believe that you can run Insider copies of Windows 10 indefinitely if you are in the Insider program, but I don't know whether you can join that at the moment.

Home page - Windows Insider Program

It was easy to join from a Windows PC, but I don't know how it works without one. (There must be a way, considering the number of posts I've seen from people who are angry that they aren't being given a full Windows 10 license as reward for participating in the Insider program.) It requires setting up a free Microsoft account.

The cheap way to legally acquire Windows 10 would have been to buy a machine with Windows 7 or 8 installed and get the free upgrade, or to buy a PC with Win 10 pre-installed on or after 29 July.