If you are not familiar with Wine (or maybe even if you are), you may find the article Understanding Wine helpful. A more complete reference is the WineHQ Wine User's Guide. Also see the Wine List of Commands.
All Terminal commands in this document have been validated by copy/paste from this document into a Terminal window and executed. Consider arranging your browser window and your Terminal window side by side in order to copy/paste the Terminal commands.
Start here: Prepare Debian to Install Wine
Before installing Wine, sudo and apt-transport-https must be installed. However, Debian will attempt to install these from a CD or DVD, which will fail if you installed from a USB drive and have no installation optical disk. One way to avoid that problem is to disable access to CDROM repositories.
Disable CDROM repositories
If you installed Debian from an optical disk, instead of following the procedure in this section, you can load the installation disk into an optical drive and continue with the procedure in Install sudo and apt-transport-https.
If you are not using a Debian installation optical disk to install sudo and apt-transport-https, do the following to remove the option to access local CDROM repositories. With CDROM repositories unavailable, Debian will download missing packages from online repositories.
An alternative to the following procedure for making CDROM repositories unavailable, for those who are comfortable editing system files with a command line editor such as nano or vim, is to insert a # character at the beginning of the line in /etc/apt/sources.list that begins with "deb cdrom: …". The added # will comment out that line and disable CDROM repositories.
Install sudo and apt-transport-https
Open a Terminal window and login as super user.
$ su -l
Update and do the installations.
# apt-get update
# apt-get install sudo
# apt-get install apt-transport-https
Enable sudo for your user account
In the following command, replace your-user-name by your own user name.
# adduser your-user-name sudo
Log out of the root account and close the Terminal window.
Close any open apps.
In order to activate sudo for your user name, Restart your Computer. When logged in again, continue from here to verify sudo works.
-------- Waiting for computer to restart --------
To verify sudo works, open a Terminal session and issue the following command.
$ sudo echo 'Hello'
The test is successful if, after requesting and receiving your password, "Hello" is displayed.
Add repository and install Wine
See if 32-bit architecture is already installed. The following command should respond with "i386"
$ dpkg --print-foreign-architectures
If it does not display "i386", execute the following.
$ sudo dpkg --add-architecture i386
$ dpkg --print-foreign-architectures
Get and install the repository key.
$ wget -nc https://dl.winehq.org/wine-builds/winehq.key
$ sudo apt-key add winehq.key
Use the next three Terminal commands to add the Wine HQ repository for Debian 9 Stretch to the operating system's list of repositories.
$ echo 'deb https://dl.winehq.org/wine-builds/debian/ stretch main' > /tmp/winehq.list
$ sudo cp /tmp/winehq.list /etc/apt/sources.list.d/
$ rm /tmp/winehq.list
Execute the next command to update packages, but …
… if you are using a Debian installation disk as a local repository, first load your disk into the optical drive.
$ sudo apt update
The next command will install the current stable version of Wine. However, some Windows applications may work better with a more recent development version. If you need or prefer the most recent development version, replace winehq-stable with winehq-devel.
$ sudo apt install --install-recommends winehq-stable
If apt complains about missing dependencies, install them, then repeat the last two steps (sudo apt update and sudo apt install).
Verify the installation succeeded.
$ wine --version
Now that Wine is installed, take a look at the article Using Wine for information on installing Windows applications.
There is also an article CSS HTML Validator installation with Wine which contains specific instructions for installing and configuring CSS HTML Validator.