Need help coding vba in Excel: copying from one sheet to another

Hello everybody,
I am new at VBA Excel macro coding and I am kind of having problems doing a, so probably, simple coding.
Since I am an newbie at this, I am apologizing for the obvious mistakes and also thank you in advance for the patience and the help!

I have an excel where I have two active sheets - Input and output.
in the first sheet (called Input), I have four columns with a list of keywords. every column has different keywords.
what I want to do is to copy from the Input (1st sheet), the first column to the Output (sheet nr 2), starting in column 1, row 1 and then, do a 'scanning' till it finds an empty cell and forwards to the next column.
repeat this for the next 3 columns in the 1st sheet but, adding it always to the Output, 1st column, after the previous copy.

I want to do this with a while cicle. Probably I will have to do a while inside of a while to go through all the columns and all the rows. (At least this is the way that I see it!)
I have tried to work with the while cicle in a simple example, but still I haven't succeeded!
(I thought that if I understood the simple example, I could adapt it to the one I really want to do, but... no luck yet!)

Can anybody PLEASE help me!
Thank you in advance