How to use the BCB read and extract the EXCEL form content?

Analytic:
I want to read a EXCEL the content of the first and third columns, and bring up this two columns of extracted, the process is:

(1) in accordance with the prescribed path I find forms, extract the first line of the first column, the first line of the content of the third column of the two cell, preserved, and then to the second line, in turn down

(2) the first and third columns when detected is empty, the end of the process

My difficult points: (1) although the whole process a general train of thought in my heart, but the specific implementation do not know how to start, don't know which pointer hui used? Function? Or something else?