adding how to add a file

docs/03-markdown.md

@@ -64,7 +64,27 @@ Where the `../images/filename.jpg` part is the path to the image relative to the
 > * From an folder (ie. `docs/assignments/week01.md`) page you will refer to it as `../images/filename.jpg`
 > The `../` part simply tells mkdocs to look for images in the parent folder, we can repeat it to go in the parent’s parent folder, etc. i.e. ../../images/filename.jpg
 
+### How to add a file
 
+The following is the markup to add a file to your markdown files.
+```markdown
+![Some alternative text](files/filename.stl)
+```
+
+Where the `../files/filename.stl` part is the path to the image relative to the markdown file, `.md`.
+```
+<back-on-folder> / <folder> / <file-name>
+```
+
+> **Note on finding the path of your file**
+>
+> If you uploaded your file inside the docs/files folder:
+>
+> * From the `index.md` page, you will refer to the image as `files/filename.stl`
+> * From an folder (ie. `docs/assignments/week01.md`) page you will refer to it as `../files/filename.stl`
+> The `../` part simply tells mkdocs to look for files in the parent folder, we can repeat it to go in the parent’s parent folder, etc. i.e. ../../files/filename.stl
+
+*Files must be uploaded in any of the universal interchange formats for 2D drawings and 3D models such as: SVG, EPS, PDF, DXF, STL.*
 
 ### How to add a video