It’s common that beginners say “I have breakfast” as “Yo tengo desayuno” which is the literal translation. But we actually have a verb to say “to have breakfast” which is “desayunar”. Same with “to have lunch and dinner".
The verbs: desayunar: to have breakfast almorzar: to have lunch comer: to have lunch, to eat cenar: to have dinner
The nouns: desayuno: breakfast almuerzo: lunch comida: meal cena: dinner
You can either say “almorzar” or “comer”, depending on the country. In México, our main meal is the afternoon, around 2-4:00 PM, so it’s more common to say “comer”, “almorzar” sounds like having brunch. But if your main meal is in the evening, the dinner, you can say “almorzar” to say “to have lunch”.
So, “tener / comer desayuno”,is not correct, sorry ): People can understand, but it doesn’t sound natural.
So these verbs are conjugated the same way as any other verb, “almorzar” is a little irregular, but not so much.
Desayuné huevos con jamón. - I had eggs with ham for breakfast.
¿Qué vas a almorzar? - What are you going to get for lunch?
¿Ya comiste? - Have you had lunch (already)?
¿Dónde quieres cenar? - Where do you want to have dinner?
¿Qué quieres desayunar mañana? - What do you want to have for breakfast tomorrow?
Ayer almorcé con David. - Yesterday I had lunch with David.
¿Qué comiste? - What did you have for lunch? / What did you eat?
Cenaré con mi familia. - I will have dinner with my family.
Estoy desayunando. - I’m having breakfast.
Tengo que almorzar pronto. - I have to have lunch soon.
Me gusta comer en este restaurante. - I like to have lunch in this restaurant. / I like to eat in this restaurant.
¿Te gustaría cenar conmigo? - Would you like to have dinner with me?
Some sentences with the nouns.
Gracias por la comida. - Thank you for the meal.
Este restaurante hace los mejores desayunos. - This restaurant makes the best breakfasts.
Sólo puedo llamarte a la hora del almuerzo. - I can only call you at lunch time.
La cena estuvo deliciosa. - Dinner was delicious.
Necesitamos comprar ingredientes para el desayuno de mañana. - We need to buy ingredients for tomorrow’s breakfast.