if necessary. If you plan on wiping your current computer's hard drive to install Windows 7, consider backing up your computer's files to a hard drive before proceeding. In order to download the Windows 7 installation file (ISO), you'll need to enter your Windows 7 product key on the Microsoft website.  The product key is typically found on your Windows 7 installation disc's packaging. If you installed Windows 7 on a different computer, you can find the product key there. The product key that accompanies most computers which have Windows 7 pre-installed is not considered a valid key by Microsoft. Buy or find a USB 3.0 flash drive that can store at least 8 gigabytes of information. This is the pen drive you'll use to install Windows 7. Microsoft has a dedicated USB creation tool that you can use to burn your Windows 7 installation file onto a flash drive:  Go to the Windows USB creation tool page. Click Download in the lower-right side of the page. Check the box next to your installation language (e.g., the one ending in "US" for English). Click Next in the bottom-right side of the page to prompt the download to begin. Install the tool by double-clicking the downloaded file and following the on-screen prompts. if you like. If you want to install Windows 7 without removing the currently installed operating system, you can create a space (or "partition") for your Windows 7 installation on your hard drive. You'll use the built-in Disk Management program to do this.  Make sure your hard drive has enough space on it for you to do this. You should have at least 50 gigabytes of free space for Windows 7, though 100 gigabytes or more is preferred.  You can also buy an external hard drive and install Windows 7 onto it. The BIOS key is the key you'll need to press when restarting your computer in order to open the BIOS, which is a crucial step in installing Windows 7. To find your computer's specific BIOS key, do the following:  Find your computer's manufacturer name. Open a search engine (e.g., Google). Type in your...

TL;DR in Chinese:
如有必要，备份你电脑里的文件。 找到Windows 7产品密钥。 获取U盘。 下载并安装USB创建工具。 如果你愿意，可以将硬盘分区。 找到电脑的BIOS键。