three columns with different categories

Hi,

I’d pretty new to wordpress, but used to building websites. Although many of them using mere html and css…
Now I’m trying to adjust my own wordpress by, what I think, is a little php coding. But I just can’t figure out how to fix it.

The thing I’m trying to do is to make 3 side-by-side columns, where each column represents a different category. Then, when posts get placed in these columns, the posts show like:

1a | 1b | 1c
2a | 2b | 2c
3a | 3b | 3c

I tried to code something into the index.php, but got stuck at this point, where every posts creates a new div instead of just entering an excisting div (eg. column 1, 2 or 3)

Can anyone please help me? I’d say it should be pretty simple to fix this, but I just can’t figure out what to change, or do.

Thanks in advance!