There is simple steps for installing the QCAD.
First download qcad form this link.
Now follow these instructions
Installation using the installer (.run)
The recommended way to install QCAD on a Linux system is on the console. Please open a console application such as Konsole or xterm. If you have a CD ROM, insert it into your CD ROM drive and copy the correct file to your hard disk. For example:
cd /mnt/cdrom/installation/linux cp qcad-3.x.x-pro-linux-x86_32.run /home/myname
Replace ‘myname’ with your login name. The exact location where your CD ROM drive is mounted might be different and depends on your Linux distribution.
Navigate to the location where you have copied or downloaded the installation file. You can use the command cd for that:
Now install the file by making it executable and run it:
chmod a+x qcad-3.x.x-pro-linux-x86_32.run ./qcad-3.x.x-pro-linux-x86_32.run
This will create the directory /home/myname/opt/qcad-3.x.x-pro-linux-x86_32 which contains the QCAD application.