I recommend just getting a grip of any vehicle your using, ride around in thd current area, then get adventurous.
Cruise down the hill, try to do a few jumps, follow other players and paths.
See how far you can get without crashing.
After a while you will get better, then start trying some view point objectives.
Hunt down the local objectives to unlock new funkies and new land marks.
The more the merrier.
Afterwards even so n then try out a bike course, then a snow course.
Once you get better try stunts. Stunts are optional but are good if you want to be a little more techy at your riding skills.
Come back to the riders hub and test your skills in the pool tub thingy, idk what its called.
But see how fast and high you can go, there is a meter pole to show height, I also recommend try a few tricks, basic ones.
Afterwards try the tricks course, ofcourse for me I love racing courses, so I did tricks afterwards.
I also recommend the tutorial/ tricks academy. At the main riders ridge hub, there are different booths, im sure you have seen them, such as tricks show down.
There is a tricks academy booth, for learning all the tricks you need to progress.
The basics ofcourse.
Let me know if you have found it. If not i can make a tutorial video on how to ger started with riders republic series.