Updating Excel spread sheet

I've been playing with creating a text file which is imported into an Excel spread sheet. I get good results when the spread sheet in empty but importing to an existing spread sheet(which is what I want) gets totally unexpected results. My question is, are there Excel commands that can say "place this data at this location?". My theory is that with such commands I can update specific locations with the extracted data. Thanks John... 

 

Looks like I should add more to my question. The question is about using text to update an Excel spread sheet, sense no one answered I suspect what I want can't be done with a text file. Are there other (simple?) techniques that can accomplish updating specific data in a spread sheet?