USB and serial port read data and VB2008

Hi friends;
I am new to this field But its very important for me to learn about this and do a practical for learning. I develop a database application GUI sucessfully in VB2008. Now i want to read the data from serial or USB port and set into textboxes.
I am electrical engineer and want to know how i can do this task sucessfully?
What is the basic hardware need and how i calculate the analog to digital conversion for that particular project?
The signal is as under
4 to 20mA, 0 to 10 volt, and 0 to 11520 Hz.
Please guide me where from i start and do it sucessfully.
Thanking u i will remain
Hamad

Go and look at something like this - It looks as though that site has a video or two that talks about it.

http://www.controlanything.com/Relay/Relay/ADC

Hi friends;
I need to know from which point i start to design. What is the mathmatical calculation to design and convert the 4 to 20mA into digital signal and what parameters are in mind for design.
I always appriciate this forum to learn.
Regards
Hamad