The errors should not be related to each other, so you have 2 problems to check out.
The easiest to resolve is the memory error.
Take your extra memory out of its slot, and try the hardware test again. If the memory part passes (I think that it will), then reinstall the memory, and run that test again. Often, simply reseating that memory chip will fix that failure. If you again get the memory failure, then that chip is bad - get it replaced.
The STF error is related to your hard drive, and much more challenging. Better to take in for service. Usually, it's a failed hard drive that just needs to be replaced. Your iBook needs to be disassembled to get at the hard drive. Could be the hard drive, or the ribbon cable that connects that hard drive to the logic board. Sometimes neither fixes, and the logic board needs to be replaced.