I have produced a super quick video that shows how to enable Remote Desktop on a Raspberry Pi. It assumes you already have your OS installed and up to date with regard package management.
You can find it on YouTube here:
https://youtu.be/JJsnAssE1eg
The RealVNC application can be downloaded from the following link:
https://www.realvnc.com/en/connect/download/vnc/
If you do need help installing the operatoing system from scratch I do have another article and video dealing with that as well. It can be found here:
http://www.grumpyoldtech.technology/blog/Installing_the_OS_on_a_Raspberry_Pi