At my past job, I got this question asked a lot about how to use the V-Lookup function. The confusion was in how the function searches the 'Table-Array'; most users believe the function searches the entire table in the vertical direction. However, this is not true, since it ONLY searches the first Column in a row-by-row pattern. Once the item is found in question, the V-lookup will then return the answer based on the column-index.
Now, the H-Lookup function is nearly identical to the V-Lookup function with one difference; instead of Vertical lookup, it uses Hortizonal lookup. But, again, the actual search occurs ONLY in the first row in a column-by-column pattern.
FYI: I have also provided a short video, if you want to learn more, about using the V-Lookup function; http://youtu.be/ZhBDz110QnA.
I have attached an Excel worksheet showing the use of the V-lookup and H-Lookup function in the first tab. Feel free to download and use this sample spreadsheet.
Let me know if you have any questions about the use of the function.