A TEFL Certificate is given after following a separate course of instruction. You can take the course at a local TEFL school which offers it or online.
Do a search for TEFL certificate and you'll come up with loads of providers. Some are good and some are bad; take a look at a review site like Reviews of TEFL, TESL, TESOL, CELTA and other ESL/EFL Teacher Training Courses. Online, Weekend & Long Term Courses Reviewed. to see what comments former students have made.