Finding out what Network Interface Card you have first should help.
Once you know that you can look for a driver for it but most distro's come with the drivers you need.
Run the command:
This is good for all the PCI buses in the system and all devices connected to them.
A useful command to diagnose and see what you have.
If you discover that you do not have a NIC you'll need a USB Adapter and a driver for that.
You should have a network/interface file that shows all the wired and wireless information.
In my case in the network/interface file I had to comment out the wired arguments to get my wireless working even tho I had the adapter.
I don't see an icon in the bottom tray
Do you mean you don't see an icon in the tray that is the indication for a wireless connection?