First, I wanted to show the benefit of using the Guide feature. I recently took some 360 videos while skiing with my family. I used the Keymission 360 on a selfie stick handheld without any gimbal. As any skiier knows, you need to make S-turns as you go down the slope.
Here's how the video looks on YouTube without the Guide feature:
Here's how the video looks on Facebook with the Guide feature:
As you can see, although the Guided video is nowhere as good as having a gimbal, it's much easier to watch than the same video without the Guide.
Fortunately, using Guide is pretty easy. It can be done as you upload a video, or it can be applied to videos that have already been uploaded (it seems to work only on recently uploaded 360 videos though). In your video, click on Options and select "Edit this 360 video"
On the next screen, click on 360 controls, then play the video. If you want to reorient it at any time, just pause, reorient it to the view you want, then click on "Add point" on the upper right corner:
BTW you can also adjust the field of view on the right side. When there's lots of movement, I personally find it better to use a wider field of view.
When you're done, just click on Save. That's it. The change will be applied right away. No need to re-upload the video.