Then, once you've booted back into the Unibeast menu, input the necessary boot flags, and try starting OS X once again.
Check out our list of common boot flags and our guide to fixing boot problems with verbose mode for reference.
Click the "Erase" button at the top of the window, give your drive a name, set the Format to "OS X Extended (Journaled)," set the Scheme to "GUID Partition Map," and erase!
Alternatively, you can split the hard drive into multiple new partitions by using the Partition button (this will also erase the drive).
If you do not manage to reach the Unibeast menu, check your motherboard's BIOS settings to make sure that the changes you made in Step 4 were properly applied.
If all else fails, try using a different USB drive for Unibeast.
At the Unibeast menu, select your Unibeast USB drive (it will probably be represented by a picture of an "External" drive) by using the arrow keys on your keyboard, and then press the enter key (or return key) to start the OS X El Capitan installer.
Also, after installing Mac OS X, you may have to sync your clock on Windows with Mac OS X.
Essentially, the BIOS (or UEFI) is the settings page for your computer's motherboard.