Restart your computer, enter the BIOS/UEFI menu, and select the USB drive to begin the live session or installation.
The safest way to acquire Ultimate Edition is through its official project pages, which provide both direct ISO downloads and official BitTorrent links: Download Ultimate Edition torrent
Use a tool like Rufus (Windows) or BalenaEtcher (Cross-platform) to "burn" the ISO onto a USB drive. Restart your computer, enter the BIOS/UEFI menu, and
Using the official torrent file provided on SourceForge is often better than a direct download because: Restart your computer
Torrent clients automatically check for "corrupt" data pieces during the download, ensuring your ISO file is perfect.