Open an account with any of the brokerages you listed.I actually have all 4, but I prefer Vanguard. You could do Robinhood since you are a beginner. Open an account and it will ask you what kind of account you want to open. You select the account, transfer money into the account. Once you have funds available search for the ticker symbol and buy the shares.
Definitely wanna buy some gold and silver right now. Lots of talk going around that they may be bringing the gold standard back and precious metals will are likely to shoot up in price