Welcome to BASIC8, when you start up your program you can click the + icon next to all the games to create an new project. You can delete all the code since we will be adding in our own code. First of all we are going to need a screen to work with, something that runs our code, to learn about that view Tony Wang's Understanding Main Loop And Driver guide. For now we will just use this code:

def update(delta)
enddef
update_with(driver())

Now when you run your project using [CTRL + R] we will have an empty screen, lets add some text in. We will be using the "text" function.
for instance:

text 0, 0, "Hello world", rgba(255, 255, 255)

This is the code we will be using, first of all we tell basic8 what to do (text), next up we give it a position, (0, 0,). After that we tell it what text to add on our screen ("Hello world"), then we give the text a color. rgba(255, 255, 255). Add in your line of code in between the update(delta) and the enddef functions like this:

def update(delta)
text 0, 0, "Hello world", rgba(255, 255, 255)
enddef
update_with(driver())

Hopefully this will help you get started on using BASIC8, for more info you can always press [F1] for an BASIC8 manual