How do I spread thumbnails instead of stacking them

[cawnpore]

On my forum, whenever I post thumbnails using bb codes, they end being stacked
example
1
2
3
4
How do I post them so that they are spread out in the box instead of being stacked?
example
1 2 3 4


--------------- Added [DATE]1363442006[/DATE] at [TIME]1363442006[/TIME] ---------------

Just to make it clear, I want images to spread horizontally as in following picture


In my case they are stacking vertically