OK, first is this a USB stick (pen drive)? If so you are good there.
Does it have data on it? If it does, back it up, because the media creation tool is going to format it, make it bootable and copy the Windows 10 install files to it. So any data that is on it will be gone after the media creation tool is finished with it.
First step after running the tool is the Licensing Agreement, no choice here, you have to Accept Next it asks you if you wish to Upgrade this PC or Create installation media for another PC. Select the latter.
Now it asks you to select the version of Windows 10 installation media you want. It defaults to what it thinks you need for the PC you are building the media on. If the computer you are using to make the media on is close to what you want to install in, there is no need to change anything here. However lets say the "broken" computer has 32 bit Windows on it, but the laptop you are building the media on is 64 bit, you will need to change it. So look at the three options (Language, Edition, Architecture) and make sure they match what you have on the target (broken in this case) PC. So if you have an English version of Windows 10 Pro in 64 bit, then that is what needs to appear under those three choices. If you need to change anything from what it's defaulted to, you'll notice that the options are greyed out. Just uncheck the Use the recommended options for this PC checkbox. Once this is done click Next.
This step has you select the media. The easiest is USB pen drive, but if you have a DVD burner on the computer you are doing this on, and you have a blank DVD, you could make a DVD if you so wish. If you chose a DVD, it will open a window to let you select the location you want the ISO to download to. If you pick USB, it will go to a screen where it shows the available removable media. If the USB stick was plugged into the system prior to reaching this step, then hopefully you'll see it there (to make it less confusing, only have one USB storage device connected). If you reached this step but didn't have the USB stick in yet, then plug it in now and hit Refresh drive list. It should appear and if it's the only device it will already be highlighted. Click Next.
At this point you'll see a progress animation start, this is where the media creation tool actually downloads the install files from MicroSoft. This will take a little while depending on how fast your connection is. Mine takes about 4-5minutes (50M bits / sec download speed here). When it 's finished downloading, it will verify the download (making sure it wasn't corrupted),, the time this takes is dependent on the speed of the computer doing it. At 50% it's done verifying and begins to copy the data to the USB key. At 100% the key is ready. You should be able to browse it with File Explorer and see it's contents. Click Finish and you're done.
Once you've successfully completed this, let us know and we can guide you through the rest.