Try doing a search for local Pros.

Then go to school for a degree in design. Ole Miss has a degree program, or the University of Memphis. Design is FAR more than playing with pretty colors. There are home safety and building code issues that you need to internalize first.

If you want to be a Designer it takes a degree as mentioned above but if you just want to decorate this can be done without a degree because all you are doing is choosing furniture, drapery, colors etc. if you have a flair go for it. Just remember dealing with clients is not all fun and games sometimes.

Just as aside I would have put the mirror above the fireplace and the art above the cabinet and the art work is hung too high you want the center to be at about 5" It is usually always hung too high.

Houzz is a good place to explore your creativity and learn some "tricks-of-the-trade." You can make yourself some business cards and get some magnetic signs for your car, check on opportunities to work with a large furniture store, volunteer to arrange the pastor's office or house at your church. Decorate for someone's party or style vignettes for a local antique shop that may just have stuff lined up on the walls. Lots of ways to start getting your name out there.

Start out playing on houzz giving advice here...definitely a lot of people looking for help where you'll be able to unleash your creativity. eventually just go for it! Looking on the "find a pro" section of houzz, there seems to be quite a few talented designers so I would definitely say there is a demand.

The best advertising is a good portfolio on your website. To build it, ask friends and family if you could redo a small room for them. They would purchase materials but you would do the design and implementation at no charge. Take before and after photos. These don't have to be expensive projects, especially if the before is drastically in need of help. These photos will demonstrate what you can do with a "challenged" room. You could do a small guest room, or bath or porch. This will take time to build but you have to start somewhere. Along the way, you may get references for new clients. Also, invest in a good photographer (or barter for your services). This is important to make sure your website looks professional. Anyway, best of luck to you in your new career.