# Download SDK
This guide sets up a dev environment for apps and libraries in 90s.dev/os/.
To get a “hello world” sample app working:
-
Extract helloworld.zip to
helloworld/
somewhere -
Mount
helloworld/app
and name the driveapp
and click it -
Click
helloworld.app.js
(it may take a sec) -
Open
helloworld
in your favorite IDE -
Change some text or something
-
Click the app again in
filer.app.js
Congratulations, your hello world app works!
The entire core and all system apps are included in the zip. This way you can see how the system works internally, and even fork and modify built-in apps.
# Next steps
-
Check out the Hello World guide for a full breakdown of the sample code.
-
Go through the Publishing guide to learn how to share your creations.