A class in spelling and grammar is a good place to start. Sorry if that sounds crass, but those basic skills are essential for a job. If you want to work in an office environment, then you must learn those skills. You cannot rely on spell check, it's not foolproof.
As far as an education, consider an associates degree. Many community colleges offer 2 year business programs. Find a program that includes classes on Microsoft Office, basic accounting, marketing, intro to HR and other pertinent business skills.
Unless you want to move to China and make the clothing, working in the fashion industry generally requires 4 years of design school, plus an apprenticeship.