Generally going with the cheapest option is just fine to get started you can upgrade later normally hassle free.

This screen will allow you to see more visually what you are purchasing 

When setting up a VPS you choose what OS you want,

 For this we will need Ubuntu and select the latest version

Here you can choose where you would like to host your VPS for the fastest we suggest ones nearest you

On the next screen: OPTIONS you can skip this unless it is of use to your specific needs

Here you will confirm your order 

Finally you will signup/signin and pay for your vps