How do I buy commodities?

Excuse me, could you please elaborate on the process of purchasing commodities? I'm particularly interested in understanding the steps involved, from researching the market to executing the actual transaction. Are there any specific platforms or exchanges that are recommended for beginners? Additionally, what are some key factors I should consider when making a decision on which commodities to invest in? Lastly, are there any potential risks or challenges I should be aware of before diving into the world of commodity trading?