The answer to your question is: it takes anywhere from 4 months to a year for an adult to train and certify to be a welder. Welders need to know different tools, materials, and techniques to get the job done. They also need to know how to read blueprints, how to follow safety procedures, and what quality is expected for different welds.
To work for a large company, you will be expected to have a basic education in welding where they will teach you about materials and technique.
Some high-school vocational programs provide this kind of education. I see that the El Paso Independent School District has a two-year program which culminates with you being able to test for your American Welding Society certification. More information can be found at https://www.episd.org/Page/3354
Many community colleges have a one-year program to teach you these things, and sometimes there are private training facilities in your area. I see that El Paso Community College has a welding training program: https://www.epcc.edu/Academics/AdvancedTechnologyCenter/welding-technology
In most training programs there is a fee for the training, and often you need to pay lab fees for the materials to practice on.
Once hired, many companies also have their own procedures, and they will train you on the job. This often is in the form of being paired with an experienced coworker to show you how each welding job is done and what is expected.
Stephen recommends the following next steps:
- read the website for EPCC's welding classes for information on what you'll learn
- talk to a career counselor or welding teacher about what kind of jobs there are in welding
- find videos on YouTube about "a day in the life of a welder" to see what they do and why people like their jobs
- talk to school counselors about what training programs may be right for you, and how you can work towards getting into those training programs