First of all heads off, for your first track! There have been way worse over the years..
SX1:
Probably my favorite track out of the three, it flows really well and feels like you spend the most time on.
SX2:
The jumps are all a bit rounded off, kinda like big rollers. Maybe this was your intention but it feels a bit off compared to SX1.
SX3:
Honestly this track feels a bit rushed, the jumps feel better than on SX2 but the sand section doesn't feel sandy at all.
Maybe you could have added a few ruts in there to give a sand feeling.
The overall layouts, sections and also the decals and billboards you used are really well put for your first track!
If you added a skybox the environment would be top notch.
Last but not least something I noticed with your track folders:
When I first loaded up a track it showed up all white. Thats because the reference folder in most of your files is called 'vghtrack'.
Thats just a small error that can totally happen to anybody, especially when you do it for the first time, but thats something you might want to look out for the next time.
And then if you upload three tracks that use the same decals, billboards etc. you don't have to put the png folders into every track folder.
You could have them 'vghsx1' and as long as the files in 'vghsx2' and 'vghsx3' reference to the first folder the game will find the decals anyway, kinda like your mistake with the 'vghtrack' I mentioned earlier.
This saves a lot of storage for the download.
Taking everything in, I'd give it a 7/10 for a first track and hope you will keep working on tracks!
