how to make ocr

Assuming you know absolutely nothing (you haven't given us any information), the first step would be to learn how to program. Hope that helps.

OCR in 50 words or less.

  1. Scan input
  2. Extract each item (character) from the input
  3. Apply pattern matching algorithm to each item
  4. Generate output
  5. Validate output

Have fun...

open google, find local library, ask about books on ocr, read books, win?

Creating an OCR engine from scratch demands a lot of effort. Instead of reinventing the wheel, why not make use of an existing OCR component? You'll find there are several available on the market for programmers and at least one should fit you needs. It'll save you months of work, if not years!