This is probably the most asked question I have seen about the game. When you first play the game you will see some play tutorials, you will need to complete those to open up the character adjustment window. On the PlayStation you will hit the Options button once you have completed the the tutorials, I believe you need to get bronze in the 3 race during the tutorial to complete the tutorial and open the Options. On the PC you will hit the ESC button to access the Options menu.
Another question I have seen;
Is there grinding in the game? No.
Also, be sure to sign up for Ubisoft Club (https://club.ubisoft.com), once you do you will unlock up to 10 free items that you can use in STEEP. Some of those rewards include the Crash Test Dummy costume, Red Bull Helicopter tickets, Kevin Rolland's Backpack, and The North Face Gateway Beanie.
Be sure to checkout my STEEP Playlist on YouTube, I will be updating it weekly with tips and tricks, new play videos, how-to's, etc.;