Two basic ways, through an agent once it's listed or with cash at an auction. Auctions do not permit you to preview, inspect or receive any disclosure about the homes. They require cash (certified funds) and do not allow you to set up conventional financing. There may be a Hard Money lender who will set up some short term financing for you, at a premium.
At an auction you are competing with many knowledgeable investors who do this full time professionally. If you choose to go this route, take your time and do not get emotionally attached to any specific house if you are looking for a good investment. I hope this was helpful.