Online TESL and TEFL Courses and Tutorials
The profession originally known as ESL (English as a Second Language) has gone through many changes in name. TESL (Teaching English as a Second Language) became TEFL (Teaching English as a Foreign Language) because English might not literally be the student's second language. Then came TESOL (Teaching English to Speakers of Other Languages). Though the names differ from one certification program to the next, TEFL techniques are well established. Get a certificate in one, and you can enter any program be it TEFL, TESL, TESOL, ESL, EFL, or ESOL.
If you want to teach English as a foreign language to non-native speakers, you'll need certification in TEFL. On campus, English Departments usually offer courses and certificate programs in TEFL. Online TEFL certification is available as well. Adults returning to school as well as traditional college students are attracted to certification in TEFL as it allows them to teach overseas. Since demand for TEFL teachers exceeds supply, you're likely to find a job.
TEFL, the Profession
English needn't be your first language for you to get a certificate in TEFL. Though you'll better understand your students' struggles if you've learned a second language yourself, it's not required. You could end up teaching a course in TEFL to students who speak a dozen different languages depending on whether you teach at the primary, secondary, or college level, or whether you teach ESL to adults.