We are happy to help, have you checked the scale of the drawing to make sure this is correct, this would probably be the first port of call. Secondly, we would recommend starting your design on a separate layer so this is separate from the DWG which has been imported so it is easier to determine what geometry is from the DWG and what is from your design.
When drawing a wall are you using the wall tool? Or are you using the line tool or polyline tool?
I have posted a link to our Vectorworks university which i think will really help with this process.
If you have any questions please get in touch and email us at firstname.lastname@example.org and we would be happy to help.