Ignore what it says in the readme file which is very complicated and confusing when confronted with all the options and simply follow the instructions on the link. You can ignore any errors about the lack of the /tftpboot directory.
In the line which says
sudo ifconfig ra0 inet up, replace ra0 with the interface name for your wireless card which might be different. Type ifconfig by itself on the command line and you will see a list, probably including eth0, lo and either ra0 or wlan0/1. ra0 or wlan0/1 is your wireless card.
If you have a newer Linux, once you follow the instructions and reboot, you might find that the card is still not seen by the Network Manager in the system tray (you won't see any wireless networks) and that is probably because by default Linux will load the rt2800pci (old built-in) driver and this will take priority over the one you just built. To find out, type lspci -v at a command line and see what is written next to the entry for your wireless network card. It will start with something like:
05:01.0 Network controller: RaLink Device 3060
Kernel driver in use: rt2860
Kernel modules: rt3562sta, rt2800pci
If you have the problem, the driver in use will show rt2800pci, in my case it has loaded the driver rt2860 from the driver I built myself contained inside rt3562sta.
In order to force it to use your newly built driver, you need to blacklist the built-in driver. Simply open /etc/modprobe.d/blacklist.conf in a text editor (as sudo) and then add the following to the end (with a comment to help remember why you did it!):
Reboot and the job's a good un'