Will this motherboard fit this case? Please help!

You have several types of motherboard sizes, from the biggest to the smallest the main ones are : ATX/MiniATX/MicroATX

Your motherboard is ATX and your towers accepts ATX motherboards, so it is ok.

Look at the descriptions or check the specs of your components to know :

- Case : Plastic ATX Full Tower
- Motherboard : Form Factor ATX