You should probably check out the manual of Construct 2 for help. This is a very simple task. I'll explain it as best as I can.
Right-click, create new object.
Select the Text object.
Go to your eventsheet.
Create a new event and double click System.
Double click "Every Tick"
Create an action for Every Tick.
Double click the text.
Double click "Set Text"
[quote:s7cp4bom]"Coins: " & [VARIABLENAME]
Basically, this sets the text to the word Coins: with the number of the coins you have every tick.