That is a very generic questions so I will answer the best way I can. I would recommend going on eBay first and finding a few used real estate investing courses. Start with Carlton, Sheets, Russ Whitney, or Ron Legrand.
When you are reading through the courses realize that a lot of these courses are written by gentlemen who have been out of the game for a while. The information is generic but it will get you the ideas of the basics.
Even though real estate investing seems like a pretty specific category it isn't. Buying and holding rentals, Fixing up and flipping them for profit, Short sales, lease options, seller financing, and brokering notes are just a few aspects of this business.
Once you read through those courses you will begin to get a good idea of what specific type of deals you are looking to do. I myself got started with the Carlton Sheets course and from their I have expanded my knowledge into the areas of expertise that I do.
For instance my primary specialty is to buy foreclosed (REO) properties, remodeling them and reselling for profit (Otherwise Known as flipping). I am still aware and have tried being a landlord, and doing lease options but my most comfortable feel in the market is flipping.
Reading these courses will give you a good overview of what you want to do and from their you can gain specific knowledge.
Once you decide what kind of investing you want to do you can begin to seek after specific knowledge. this would be best obtained in the field. I would join a real estate investor club and start attending their meetings. See what happens at these meeting and meet the other investors. Some of these investors will be open to an apprentice type relationship. I have taught many people this business from this very angle. I usually give them a small slice of pie to learn from me and then we do several deals together until they are ready to do some on their own.
In short though I will tell you to read, read, read, their are tons of books written on the subject and lots of materials to go over. Their are also tons of free resources so don"t feel the need to spend a lot of money.
Try the free resources first then look to spend some money when you are sure of the direction you wish to go.
Next go out and do a deal. Don't get locked in analysis paralysis. Once you have enough knowledge to feel comfortable just do it. Find a mentor in the real estate investing club to help you out or give his advice. Some wont be willing to but some will. I am always willing to help out anyone in my market that has a real estate investing question.
10+ years as a real estate investor involved in over 150 transactions.
Co- Author of 2 books.