What do you have to work with?
Do you know any computer languges?
Asm is not the easiest to start with.

You need to d 2 things
Recieve Serial
Send SPI
Look in the code library. (on the left)
You need the datasheet for the D/A so you know what to tell it.

Start with the serial port receive and echo the data to your VB program. Then work from there.

For the Hc11 if you have a chip and it is not locked you can copy it. And some times the code will work on another chip in the family. Or you maybe able to find 1 or a small lot. (Is this Hooby or Comercial I do not know how many you need.

If you just need 1 of these things and you do not want to spend the learning time on the project a Basic Stamp may be more suitable