I have a USB 2.0 header on my motherboard so can I plug that into my 3.0 port on the front of my case? I'm not sure if it'll work and don't want to spend £100 on my case and motherboard and have it not work since it is my first,budget build.
Yes, but you should use a cable to adapt it.
A USB2 and USB3 header differ, as USB3 has more pins.
Image courtesy of here
You can get a cable similar to the following:
As USB3 is backwards compatible and has a pin out compatible with USB2 devices, it's just a case of matching the correct pins on the header to the pins on the cable. Do a search for
USB3 to USB2 Header Cable Adapter, it'll be a 19 pin to 9 pin adapter (Maybe listed as 20 to 10, but one pin will likely be missing to be used as a key), there should be plenty of results.