Install Windows 7 Starter From USB On Toshiba NB500 Netbook

Hi,Ihave a Toshiba NB500 netbook,which did have windows 7 starter on in the first place.
However I decided to put windows ten on as a free download,But I don't like it and I don't think it works well at all ,So I would like to put the windows 7 starter back on.
I have obtained it on a USB which I am told you can reinstall using this.
However when in the BIOS,There is no USB boot up option.
Now I am no computer person really,so to be honest am rather lost with this,can someone tell me how to do this in simple tearms,As it stands its not worth having it done due to the cost involved,as its only a second laptop,but it would be nice to be able to get it back to how it was .So if anyone can help it would be appreciated Thanks.Goldman

Have you disabled Fast Boot, changed from UEFI to Legacy aka CSM Support and made sure the USB drive is in a USB 2 port ? Have you also checked under HDD to see if the USB device shows there ? If so, We'd need to know How you created the Install USB. You may also need to post some pics of the actual BIOS pages as I can;t find any usable ones.

Thanks for the reply,it is set in normal boot,How do you change from UEFI to Legacy with CSM support??.
As I said I don't really know much about this sort of thing,the USB with windows seven on was obtained off ebay,.
Although I am in the BIOS I don't seem able to do a great deal,You say to check under HDD to see if USB device shows ,well I don't seem to be able to see anything there.
Trouble is I don't really know enough to be messing with it I suppose.
Thanks goldman..

Please give us ALL information about the netbook. Does it has a ODD? Does it has a HDD or SSD? How big?
Do you have a BIOS option to do a Factory restore?
Toshiba NB500-108 - Toshiba
mention a Toshiba-HDD recovery

Hi just an update,i have now been able to do the windows 7 install via USB.
To do this I kept pressing F12 repeatedly while turning the netbook on,this brought up a small Boot UP option,the first time it didn't see the USB in,So I turned it off Put the USB in First then Started it up again,This time the USB was there,And I was then able to install the windows 7,Which has now been done.
That's it in a nutshell