First, inspect the wiring from the battery for wear or exposed wires - a 450 volt shock will knock you out (literally) or could even kill you.
The closer you are to your subject, the more effect the strobe will have. As you move away, you'll rely more on available light (daylight).
There are no hard and fast rules in photography, just techniques, art, fun and learning. Since this flash is a bargain, get it and use it until you're tired of using it. That's the only way you'll learn what works and what doesn't work.
In other words, you probably want some stop-action photos. You'll find that if you're standing near the line the skater follows, you'll have less apparent movement as he bears down on you or away from you. If you're standing perpendicular to his line, you'll get more movement as he sweeps past you.
If you want minimal flash effect (which would show some blurred movement but also a clear image - very effective at showing speed AND clarity) you'll have to move back gradually with the flash. Take 10 shots, each at a different distance from your subject, and modify the zoom and aperture (lens opening) to get proper size and exposure (you're probably not concerned with depth-of-field, which changes with aperture). You'll see that the flash has less and less impact, but the image size is the same, while the blurriness increases with distance. Inspect your photos -- they have shutter, aperture and flash info embedded in the file so you can make sense out of what your settings were.
Depending on the camera model, you may be able to change the shutter speed and still get the flash to work. Faster shutter speeds will stop the action more.
Your real problem won't be seen until you try this for a while. Shutter lag is how long it takes to capture a photo after you press the shutter release button. Check your camera -- many have 'sports' settings that take a rapid series of shots automatically. Since you have a pro flash (rather than a consumer flash) you can take flash photos instantly (that's what that big honkin' battery is for).
Experiment. Try different things. Learn. Have fun. Create.