Most recent notebook does not recognize bootable USB, so it is hard to install new OS since some notebook do not have DVD drive. The other problem is new notebook comes with EUFI BIOS which most of the time will not allow you to install certain Windows version such as Windows 7. So here is how you can fix it:
1. Open BIOS (upon restart press F2 for Acer, other model might use different key such as F6, F12 and DEL)
2. Look for setting which allow you to change from EUFI BIOS to LEGACY.
3. Press F10 and then hit ENTER.
4. Upon restart press F12 and select your bootable USB stick from the Menu.
Now you can proceed with Windows 7 installation.
If you have problems, details instruction can be found here: