New notebook wanting to upgrade from windows8 to windows 7

It’s an acer aspire E1-510-4899.I have done many fresh installs in the past,BUT this does not have a disk drive.I do know about changing boot options to usb,BUT when i try it says that this notebook does not have this option.
I need to know if there is another way to do an operating system change.The link below shows the specs,except mine has 8gb of ram and intel quad core N3520 http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=8585475
Thanks for any help
Answer #1
This is from another forum …
“It has a new BIOS type which is not very helpful with non Windows operating systems. I needed to change to Legacy Bios and disable secure boot to be able to install …”
So it looks like there is an option to change to legacy bios which will have the usb boot option.
Answer #2
^ This.
Answer #3
Thanks for the replies.I will try tomorrow.
Answer #4
Downgrade windows 8 to Windows 7 Acer Aspire E1-531 http://www.youtube.com/watch?v=Bknq6pSoZro
Answer #5
I have messed with this for about 4 hrs now,and no success.The secure boot is off now,but it will not give me a drop down menu for legacy bios.It won’t let me delete partitions.I have watched so many ways to do this,that i am just confusing myself now.Any other suggestions?
Thanks very much