Sorry, you have to use the terminal. It is the easiest to provide help over the internet, don’t be scared of it. We will get you through this. 
So what we are going to do is:
- Identify the usb qube
- Identify the modem
- Find out how to use it
- use it
1. Identify the USB qube
First, you have to find the qube that has your USB devices.
There are 3 possible qubes that could have them.
- (dom0) No sys-usb
- (sys-net) sys-net as sys-usb
- (sys-usb) sys-usb
You can choose this in the setup. If you know your USB qube, skip to 2.
Try this: Click on the qube icon in the upper right corner to list your running qubes. If there is a sys-usb qube running, you have sys-usb. Skip to 2.
If not, click on sys-net → Run Terminal.
Run:
lsusb
in sys-net.
Here is an example output:
Bus 005 Device 004: ID 0000:0000 Realtek Semiconductor Corp. Gigabit Ethernet Adapter
Bus 005 Device 002: ID 1111:aaaa Some corpo, Inc. USB3.1 Hub
Bus 005 Device 001: ID 2222:bbbb Linux Foundation 3.0 root hub
Bus 004 Device 006: ID 3333:cccc some corpo, Inc. USB Billboard Device
...
If it looks like that, sys-net is your USB qube. Skip to 2.
Here is an example for when lsusb returns nothing:
[krakin@sys-net ~]$ lsusb
[krakin@sys-net ~]$
If it looks like this, dom0 is your USB qube.
Confirm this by clicking on the qubes menu in the upper left corner → Run Terminal.
Run:
lsusb
in dom0.
It should display something like the example. If not, something is wrong.
2. Identify the modem
In your USB qube open a Terminal.
You can do this over the start menu:
- dom0: Run Terminal
- sys-net: sys-net → Open Terminal
- sys-usb: sys-usb → Open Terminal
Run:
lsusb | grep Huawei
and post the output so we can determine the next steps.