Sounds easy enough, and here are the steps:

1. Firstly access the settings file of SVN through the Tortoise context menu (right-click).

Tortoise SVN context menu showing how to access the Settings file

2. Enable automatic properties in the miscellany section.

[miscellany]
enable-auto-props = yes

3. Add the file extensions and keywords you want to be activated.

[auto-props]
*.html = svn:keywords=Date Id Rev Author URL
*.js = svn:keywords=Date Id Rev Author URL
*.css = svn:keywords=Date Id Rev Author URL
*.php = svn:keywords=Date Id Rev Author URL

Tip: This works only on new files added to your repository after the configuration has been modified.