I am a complete novice and have just installed Ubuntu on an old laptop and connected to the Internet with a cable. I need step by step instructions on how to install my USB adapter please? I have plugged it in but nothing happens!

What kernel are you running (uname -r)

Your alternatives are:
1. use a kernel >=2.6.24 (has the rt2x00 driver included)
2. build the older drivers from the rt2570-source package

The kernel version in the system log is Ubuntu 2.6.24.19.34
One of my problems is not understanding how to configure Linux or load drivers. Thanks for responding.

Well, in principle your kernel should already have the correct module. After plugging it in, try:

lsmod|grep rt

Also:

dmesg | less (and look for messages about the USB device being plugged in)

You can also see if a device entry had been created:

ls -d /sys/class/net/*

You can attempt to load the module yourself:

sudo modprobe -v rt2x00

It is possible that the module fails to load because the firmware is not available - so check the 'dmesg' log carefully and watch the screen when you attempt to manually load the driver. If the firmware is missing, use the package manager to locate it. In the Debian repository the package name is "firmware-ralink".

When I plugged in the USB device the message read rt73usb

Check the loaded modules: lsmod|grep rt

Rev. C should be using the rt2570 driver or else the rt2x00 driver. If it's using the rt73 driver then something is wrong; you can unload the driver with 'rmmod (drivername)' and load the correct driver (if it exists on the system). See the directory /lib/modules/$(uname -r)/kernel/drivers/net/wireless to find out what wireless drivers are available.