help extrude line in 3d autocad

how to extrude line with 3d autocad into the wall like this image plzzzzz

hope you know the basic of Autocad

additonal po sir render master
6. offset again the created poly line to the desired thickness then extrude again
7. move the extrude poly line inside the sliced object then Union.

very nice render master

i am newbie in autocad 3d ,but i dont understand this tutorial
i dont now how to groove this guidelines and sliced it
can you make video tutorial for this
i need this tutoarial plzzzzzzzzzzzzz