ADB is a tool for Android debugging. With ADB, you can install applications from you PC, copy files to/from your device, access console. You can access your device using an USB Cable, or through network (using an IP address).
You can take ADB from SDK  or inside <my_android>/out/host/linux-x86/bin/adb
I cannot see my device
First checkpoint must be for ADBD. It´s the ADB daemon, and if it´s not running on your device, you will not be able to access it.