docs: clarify Windows prerequisites and Vim startup

README.md

@@ -34,6 +34,20 @@ managed Bash block initializes it.
 
 ### Windows (PowerShell)
 
+Install Git, Python 3, and [Vim for Windows](https://www.vim.org/download.php)
+first. Include the console version (`vim.exe`) and add each program's directory
+to PATH. Open a new PowerShell window and verify:
+
+```powershell
+git --version
+python --version
+vim --version
+```
+
+Vim must be version 9 or newer. If a command is not recognized, fix its
+installation or PATH before continuing. If Python is available through the
+`py` launcher instead, use `py -3` in place of `python` below.
+
 Clone into your user directory, then run the Windows installer:
 
 ```powershell
@@ -41,6 +55,11 @@ git clone https://git.justconn.top/gitea-admin/dotfiles.git "$HOME\.dotfiles"
 python "$HOME\.dotfiles\win-install.py"
 ```
 
+After installation, run `vim` in your terminal or open `gvim` for the graphical
+editor. The configuration is loaded through `$HOME\_vimrc`; plugins are stored
+in `$HOME\vimfiles`. Keep Git on PATH for plugin updates and Git-based file search.
+The installer downloads plugins from GitHub, so that host must be reachable.
+
 Use `$HOME` explicitly in PowerShell: `~` passed to external commands such as
 Git may be treated as a literal directory name instead of your user directory.
 In Command Prompt (CMD), use `%USERPROFILE%` instead: