Want to get your hands on the iPhone 5C? Well, you can pre-order it right now from Apple. Alternatively, you can check with your carrier, or a local retailer, so you should be able to get your hands on one and in the colour you desire.
Apple’s own website often gets hammered into submission when new products become available to pre-order, so an alternative method may be the way to go. However, if you are determined to order from Apple, you could go through the Apple Store App if the website is failing you.