How to adjust different width for columns

In the Matrix that I've created, I need to adjust the width of the each column in a different size (one column very wide, other 2 very narrow). Like this example:

How can I do this??

Hello @AnndeGroot, I'm assuming you were supposed to post a screenshot of how you wanted it to look like. Sadly we can't see the image. If you could repost it on your thread, that would be great, here's how.

Once we have a visual reference on how narrow/wide you want the columns to be, we can give you the proper CSS Codes that you need in order to adjust it.