How to purchase STC credit?

Excuse me, could you please elaborate on the process of acquiring STC credits? I'm interested in investing in this particular cryptocurrency but I'm unsure of the steps I need to take. Is there a specific exchange or platform where I can buy STC credits? Also, what are the necessary precautions I should take to ensure a safe and secure transaction? Lastly, are there any fees associated with purchasing STC credits that I should be aware of? Thank you for your time and assistance.