Sorry it took me a while to get back here.
All of this will depend on how far you are along the learning curve of web design, web development and DNN in general. To work with DNN you have to pick up a lot of skills that you might not have wanted to learn before you started.
A requirement for changing the calendar is that you know how to work with css styles. If you do not, then you will have to get someone to style it for you, or start learning css now.
The calendar is largely styled by the module.css file in the folder where the module resides. If you check in desktopmodules\events, you'll find it. However, before you start, I would suggest trying the beta release that is linked to from another post in the forum here. It has many updates and fixes in it already and will get you further down the path than the old version will.
There is one difference in particular that matters here. The new version lets you select a custom style sheet per instance as a sort of theme or skin for the calendar. There is a theme already present in the beta called "Small". You can make a renamed copy of the theme's folder and then set about making changes to the styles present in the style sheet within, which you also rename with the same name as you have given the folder. You can select the theme from within the module settings.
Figuring out which exact classes you need to change is another drama and to help you with that there are one or two tools. You must install Firefox, then the Web Developer extension and then also the Firebug extension. These are dead easy to find on Google and just as easy to install.
When you are viewing your calendar in Firefox, you should always press Control F5 to force-load the most recent style sheet. Then, right click an element on the page and select "Inspect element" at the very bottom of the menu. This opens Firebug and displays they classes and styles affecting that element.
You can then go to the CSS menu on the Web Developer toolbar and select "Edit CSS". This opens a panel showing all fo the stylesheets in use on that webpage, including the one affecting the calendar. You can make changes to that sheet and they will be displayed in real time on the page. Both tools do the same things, but in slightly different ways. The method I've described is the way I do it.
The exact classes you need to change will vary depending on what you're doing and I can't tell you what to change. Try starting with .EventDay and setting a fixed width for each day in pixels or try setting an overall width for .Event
As I mentioned earlier, the module makes use of a lot of embedded styles and this makes it doubly hard to style. The hack is to use "!important" to force the styles to work.
There's nothing simple or easy about making things look right in DNN, so don't feel bad if it seems ridiculously hard to achieve a minor change.... it is! That's about all I can tell you.
Regards,
Rob