Google "keto" or "keto diet." You should get plenty of hits.
The idea is to start eating natural foods - stay away from sugars, starches, grains and processed foods, especially highly processed carbohydrates.
You replace sugars (and foods that breakdown in your digestive tract into sugars) with good fats. Butter, oils, mayonnaise, nuts, etc. Fatty cuts of meat, poultry, fish, eggs, cheese, etc. Green veggies - anything low on the glycemic scale.
Get a carb counter app - it's the easiest way to keep track of your diet, and log what you eat. The Adkins Diet carb counter works well. Limit your carb intake to 20 grams per day, protein to 30 or so grams per day, and the rest is something high in fat content.
Anything in a package or a bottle - read the label! Be especially aware of the net carbohydrates. Remember, you have a daily allowance of 20 grams to get into ketosis.
Good luck, and feel free to ask questions!