Hi, this is my first restoration. It's a Ford fairmont, I have an idea of the desing but I don't have experience. How can I modify de engine and Where can I Buy the accessories?
This is a very complicated question, because restoring a car requires knowledge of mechanical parts, body and paint techniques and interior plastic/fabric restorations.
For the engine, that appears to be Ford's 3.3L inline six. You can learn about some options here: http://www.mustangandfords.com/how-to/engine/1811-six-appeal-building-a-200ci-inline-six-engine-for-...
For the interior, since it's similar to the 1979-1986 Mustang you can look at this catalog to see some of what's available (you won't find everything interchanges, but a lot of it does interchange): https://lmr.com/products/79-93-Mustang-Interior-Parts
You can also use the same link above to see suspension and chassis improvements, I highly recommend subframe connectors so the chassis has less flex.