Hey Welditon,
Welcome to the forum and the best informative-packed group of welders you will find. All the gents have provided you with sound advice and suggestions to enter the welding arena and make a good living. The future for welders is very lucrative with the impending shortage of those in my age genre(63) who are getting ready to retire. Your age means nothing if you have the desire to want to learn the welding skills necessary to become proficient, productive, and "in demand" by the companies who are in dire need of really good welders. Don't hesitate to go to school and really apply yourself with a positive mindset you can learn all the different welding applications, ie; SMAW(stick)), GMAW(mig), GTAW(tig), O/A, plasma cutting, and the variables associated with each. Your desire to get better comes with practice, practice, practice.....make mistakes, they will make you better, and if frustration sets in, STOP! Take a break. It will come.
Dbigkahunna provided great suggestions to "get your feet wet".....try it.....a fab shop will allow you to do many different techniques and see the infinite configurations metal can be manipulated & welded. If you seek the premium wage arena, the pipeline, rig & structural job market will be the best....of course, the drawback will be the travel involved and time away from your family. Many considerations will come into play for you to ponder.
Since you have some metal forming & welding experience, although limited, you will find the learning curve a bit easier than someone who has no practical knowledge at all. So, you see, you already have a primer that simply needs to expand into the multiple facets of welding techniques & parameters. Believe me, I've welded for 43+ years and I still learn.....it's neverending. Come here...ask questions...read old posts...pick up as many books as you can on welding.
Here's a question to ask yourself: "HOW BAD DO I WANT IT???????". The hungriest welders make the most...and are the best...........Denny