The way this case is opened is very different from traditional cases. The side panels aren’t screwed to the rear case. To remove them you need to unscrew the top panel and then slide the panels up. Even though this case is targeted to the mainstream market, this case uses thumbscrews to hold the top panel, feature only seen on high-end cases.
Even though you can remove the right panel (the panel behind the motherboard) the metallic plate where the motherboard is installed is permanently attached to the case, so you can’t remove it to facilitate the motherboard installation.
The left side panel (the panel you remove to build your PC) has a small mesh and a duct to improve internal airflow, matching Intel’s Chassis Air Guide Design 1.1 (translation: the correct requirement for mini-tower cases). You can adjust the height of the duct to better match the CPU cooler you are using, as this duct is used for improving CPU ventilation (read our How to Correctly Assemble PCs with Pentium 4 Prescott tutorial for an in-depth look at the role of this side duct). You can also attach an 80 mm fan to this duct, if you’d like (this fan doesn’t come with the case).