"c:\xampplite\htdocs\MonSitePerso\Templates\" folder is the template for your site;

You should create the next  tree under "\Templates" (the files created are empty for the moment) :

    "\TemplatePerso\":  folder containing all the elements of the template.

    "\TemplatePerso\css\":  folder containing the css files.

    "\TemplatePerso\images\":  folder containing all images of the template.

The "\TemplatePerso\" folder contains the files:

    index.php: the structure of your template.

    templateDetails.xml: the description file of your template (author, name, list of images, etc)

    template_thumbnail.png: file for the thumbnail displayed in joomla. This thumbnail, you can create it after completion (creation and improvement) of your template.

The "\TemplatePerso\css\" folder contains:

    template_css.css: style statements sheet for displaying content in joomla (font, size, colors, borders, spacing, positioning... etc.)

The "\TemplatePerso\images\" folder includes all the image files of your template.
(N.B : for the images used in your site regardless of the template, they are placed in a higher level in the folder:

"c:\xampplite\htdocs\MonSitePerso\images\" .

This is where you place the images illustrating your articles.