In order to be able to paint well on fabric with the Faber-Castell textile markers, a short preparation is required.
Place the piece of cardboard in the T-shirt to avoid stains on the back of the T-shirt if the pen is pushed through the fabric.
Now tighten the T-shirt and attach it to the cardboard with the clothespins. The fabric should be stretched and wrinkle-free so that it is much easier to paint.

First, draw the spider and the spider's web slightly with a pencil. This will disappear the first time you wash it.

Now use the Faber-Castell textile markers to draw first the red elements and then the black elements of the motif. 
To fix the drawing, iron the T-shirt without the steam function. Your Halloween costume is ready!