Using Visual Basic to fill text box with drop down list Value

Question

Hi I am trying to produce a fillable form for COSHH which is control of substances hazardous to health. On the form will be a table and in the table there will be a drop down list in each field. The list will contain a series of codes such as H301, H333, H365 etc. Each of these codes will have a value which with be a piece of text saying what this code represents. So what I want to do is for the user to select the code from the drop down list and then its associated value to be displayed in the column of the table next to it as shown below.

H301 Explosive
H364 Irritant to eyes

I am pretty new to this stuff but I can create a table and insert the list of codes, but do not know how to extract the value and place it in a column next to the code. Can anybody help with this.

Regards

John