I’m sorry courane01 but we can’t generally help with customization requests – a good knowledge of CSS is certainly key for something like this and you will probably want to review the Themer’s Guide, too. That said, you can see that it’s possible to target and change the width of the events content like so:
.events-gridview .block-type-content { width: 1200px }
If you tidy that up and also play with the floats (and clearing of floats perhaps, in the case of the sidebar) you’ll probably be able to get close to achieving what you need here.
Hope that helps!