How to Switch from Terminal to xfce in Ubuntu Server 16.04?

Hello Guys,

I have installed Ubuntu Server 16.04, I want to use it as LAMP server.
normally I wouldn't need a GUI on the machine but at times possibly, since I am no good with Linux.

So after installtion of Ubuntu Server, I installed xfce4 desktop

sudo apt-get install xfce4

I restarted the Computer, I came to Terminal as before, from there in order to goto GUI, I tried the following:

Command------------------------Result------------------------------Description
startx-----------------------------Error-------------------------------I know it is not the command for xfce but tried it anyway
sudo service lightdm start------Error-------------------------------Failed to start lightdm.service: Unit lightdm.service not found

How can I get to GUI/ XFCE environment from Terminal?
I don't want it permanent but I want to be able to load/ unload xfce when I want.