If you haven't figured out the major keys in-game, take a look at this.
Keys
Key "T": Using this for moving content from vehicle -> person or the other way around.
Key "Y": Opens up a player menu where you can have a quick view over your current stats. This menu is also the way when you want to access your mobile, your gang & etc.
Left windows key: This key is used when you want to pickup things such as apples, peaches, weed and so on. If you want to mine anything(copper, iron, diamonds) you have to buy a pickaxe at the market.
Other
Left windows key: Furthermore when you not grabbing your hands around those fruits and such you can also use this key to interact with your vehicle if the tires is broken. (you need a toolkit for this)
SHIFT + R: Using this to detain people for your own safety or some other reason you have in mind, recommend you only do this if you have a valid reason to do so. (you need zipties)
SHIFT + G: Knocking people out. (need to have a gun)
Furthermore I would advise you to take a look at these cool guides to how you get a good beginning on the server. Good luck!