*sigh* Firstly, download the latest version of the world builder from the stickied thread in mods.
Open the script from the list of scripts, ingame. Press H for help.
You will notice it will have like ...
a key like <- then something in brackets like this: [Y]. The key in the bracket is the one you can use for laptops.
To switch to laptop controls, press K.
So from instead of using <- to do something, its now the key in the bracket next to it.