you need to install linix headers generic by:

sudo apt-get update
sudo apt-get install linux-generic

I see you already have downloaded the realtek wifi drivers make sure you are in the right directory and run this to install them:

cd rtlwifi_new
sudo dkms add ../rtlwifi_new
sudo dkms build rtlwifi-new/0.6 
sudo dkms install rtlwifi-new/0.6
sudo modprobe -v rtl8723de ant_sel=2

Congrats you have running wifi.

Save the config with this command:

sudo /bin/sh -c 'echo "options rtl8723de ant_sel=2" >> /etc/modprobe.d/rtl8723de.conf'

Restart.

Details here:

https://h30434.www3.hp.com/t5/Notebook-Wireless-and-Networking/Realtek-8723DE-wifi-module-amp-Bluetooth-Linux-driver/td-p/6477307

Install libelf-dev and elfutils package. If you are using Ubuntu or any Debian variant then use the following command to install them.

sudo apt install libelf-dev

Install libelf-dev instead of libelfg0-dev if using Ubuntu 16.04LTS:

sudo apt-get install libelf-dev

I reported the issue to Open-TEE here:

• https://github.com/Open-TEE/project/issues/23

If apt-get install Unable to locate package, It means that package you are installing may not available on PPA according to your /etc/apt/sources.list

Then You should add appropriate PPA (For Finding PPA Refer Website: http://www.ubuntuupdates.org/ppas)

Then sudo apt-get update and then sudo apt-get install [pkg-name]

For More Information About How To Add PPAs Visit: Ubuntu Help

The reason you are seeing this error is because you are trying to install a package called "install" (next to cmake and libelf-dev). This looks like a simple typo. Just remove it and it should be fixed, because "install" is not a package.