Getting Haiku up and running

I am just a beginner with Haiku, and I am still confused about a number of elementary things. I made a USB stick installer, and used it in an empty partition on a Lenovo Windows laptop. I eventually figured out how to choose to boot Haiku instead of Windows.
But the first time I did this, the trackpad did not work; I chose “try” instead of install and got a basic desktop.
I figured out that I needed to attach an external mouse, instead of using the trackpad.
But I no longer get the screen with options to “try” or “install” Haiku. Though I never actually installed Haiku, I get a minimal Haiku installation that is very very slow (perhaps because it is still running off the USB stick?).
Is there any way I can wipe the current semi-installation, and install Haiku from scratch?

If you click “Try” nothing at all is installed. The option is disappearing but all you have to do is to launch the installer; it will work as well as if it was the first time. The only difference is that it will keep the settings you made (keyboard, language, etc) .

But now, when I launch the installer, I do not get the option to install, I just get a minimal desktop even though I never installed.

On the usb install it will boot to desktop after the first boot, you can start the installer by opening the Installer application in the deskbar menu.

thanks, that works.