Adding new modules into existing block

Hello,
I would like to know how can I add new modules into an existing block. For instance. I have activated the center-bottom block, and it loads a single module there. I'd like this block to have 2 modules instead, side by side on the same row. How can I do it?
Thanks,

Dani

Hi
you can publish as many modules as you want in the same position, this is the native behavior of joomla
now to align them in this way, you must use your own custom css with a float positioning for example
CEd

I know I can publish as many modules as I want in the same position. However, when I try to insert a new module by drag & drop in the center position it doesn't allow me to. Any idea on how to solve it?
Thanks!

Dani

I think that you mix "module" and "block"
module = the modules you manage into your website with the joomla module manager
block = the blocks that you can drag and drop into template creator to create the modules positions

Sorry, now I've realized that I've messed the lines in the creator . Thanks for your help, it was my fault!