Really Bare Bones Board help!

Hi Guys,
Last week someone donated some kit to our organisation. In the kit were 10 RBBB's. I'm hopefully going to use them with school-kids on some nice hack projects.
So, I've built one of the boards. The LED is on, and when I hook up an LED to pin 13 it flashes, so I'm assuming the build is fine. With the kit came a USB To RS232 TTL UART 6Pin Serial Adaptor.
I thought I'd use that to upload to the ATmega328, and at this point I'm coming up against problems...With which I am hoping you guys can help.
I have downloaded the drivers for the adapter, and when plugged into the USB, I can see 2 new options in the Serial Ports:
/dev/tty.SLAB_USBtoUART
/dev/cu.SLAB_USBtoUART
so I can see that the port is recognised. I have an issue with the connections though....
On the USB adapter there are 6 pins:
3.3v
RST
5v
TXD
RXD
GND
On the RBBB I also have 6 pins, but they are:
First pin not labelled
RX
TX
5v
Fifth pin not labelled
G
I'm unsure as to whether I've connected this up correctly, so could do with some support on this.
When I'm trying to upload a test program to the chip i get the following message:
avrdude: stk500_recv(): programmer is not responding.
I am using:
Board: Arduino Uno
Serial Port: /dev/tty.SLAB_USBtoUART
Programmer AVR ISP
It would be great to get some support, I have done quite a few projects with an Uno, but with the influx of this kit I can do some teaching with the RBBB's when I get them working.
Thanks in advance,
Chris

Hi Nick,
Many thanks for the response!
I've checked out the tutorial you have posted and ensured that all the wiring of the USB adapter is correct. However I am still betting the:
stk500_recv(): programmer is not responding
error message.
So it's nothing to do with the wiring.
Any other ideas?
Many thanks for the support thusfar, it really is appreciated.
Chris

Post a photo of your setup then.

Hi Nick,
please see attachments. Struggling to get decent res. If not clear enough just let me know.
Thanks for the continued support.
Chris

This always happens; you are not the first - or the hundredth. OK, two things:

Firstly, you may need to swap over the "Tx" and "Rx" lines between the two as what is transmitting and what is receiving depends on your point of view.

Secondly, the marking "RST" on your CP2102 tells me that is is one of the "bogus" ones. This isn't that much of a problem, but it must be modified by cutting the track to the "RST" pin on that board (the USB to TTL board), and connecting it instead to the RTS pin on the CP2012 - pin 24.

In the meantime, perform a manual reset by pressing the button briefly (about 3/4 second) when you see the "Binary Sketch Size" message appear in the IDE. If that then downloads correctly (may need to try a few times to get it right), then the Tx and Rx are correct.

Note that you have the later version of the RBBB which has the reset capacitor already incorporated into the design.