USB port on front panlel of the case

Your board does not have a USB 3.0 midboard header so you won't be able to connect the front USB 3.0 ports directly to the board. There is no way to convert the cable to connect to the board either as far as I'm aware as there's no USB 3.0 connectivity on there.

ASUS H81-Plus Specifications

The earlier versions of the front panel with USB3 ports had a standard USB3 male connector. You were expected to route the cable out through the back and plug it into one of back ports. The problem was that most of the cases didn't provide a means to do that so you had to cut/drill a hole for the plug. That was a backyard fix and it seems case manufactures have always lagged behind motherboard manufactures in one way or another. It's gotten better but builders need to pay more attention to matching a case to the motherboard features.

With that, there's not much you can do except maybe install an accessory front panel that uses the standard USB3 male connector and route it to the back.

Alternatively if you want more USB 3.0 ports and don't mind them being on the back you could add a USB 3.0 PCI-e card.

My MSI board came with an adapter that would go from that blue usb 3.0 plug to the usb pins on the motherboard, it may not give you 3.0 ports, but at least they will work.

Looks like this.

You can get an adapter that will plug into your USB 3.0 cable coming from the front panel and terminate in two cables with USB 3.0 type A connectors on the back, You would then run those cables out the back of the computer and plug them into the USB 3.0 ports on the rear I/O panel.

Edit. I found this one on e-bay. You would probably have to add a couple of USB 3.0 extension cables to get enough length.

But then you`re taking plugs off the back, just to add to the front. And if you use the back 3.0 ports for a printer, etc. that`s not an option.

You have 6 intrenal usb 2.0 connectors on that board, I would just connect to 1 of those.

Motherboards - H81-PLUS - ASUS