abuild broadcom wireless driver

Hi -

I am following the wireless network config wiki:
https://wiki.alpinelinux.org/wiki/Connecting_to_a_wireless_access_point

I believe my network card is the unsupported broadcom one. So I am following directions at the bottom of the page:

-- Note: BROADCOM WIFI CHIPSET USERS will need to compile the firmware manually for their chipset. First, apk add alpine-sdk, then git clone aports from git.alpinelinux.org, switch to the aports/non-free/b43-firmware folder, then run abuild -r. Install the generated apk file. Run fwcutter, and you should be good to go.

At the end (after following directions from abuild setup here):
http://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package

I am trying to install the apk package in the directory. Since the only file left in the folder is called APKBUILD, I am attempting:

sudo apk add APKBUILD

and I get:

ERROR: unsatisfiable constraints
APKBUILD (missing)

Thanks.