This is right? 1)avant qu’ils visitent à quelqu’un, ils doivent acheter un cadeau.
2)après qu’ils avoir manger, disaient merci

No, I am afraid it is not.

Explanation:

1) this sentences is theoretically correct but I think you can better use as sujet et verbe; il faut.

I do not know if this is not what you had in mind but then it would be something like;

Avant qu'on visite à quelqu'un, il faut acheter un cadeau.

2) you forgot to conjugate the verb avoir.

Si le sujet serait ils, le verbe se devrait adapter au sujet.

So better would be; Après qu'ils ont mangé, ils disaient merci

answer:

hello, after writing this text in french i have to translate it into english. to those who will take the trouble to me.

before arriving at the museum, we notice a charming alley, with its stream, breathtaking greenery, hundred-year-old trees, ducks and geese, sculptures of different themes.

this museum takes up the entire history of electricity from its beginning to the present day, we appreciate the exhibitions and the references to those who were the first to master electricity and exhibit many ancient instruments of electric hope. many films and audio recording available to explain the operation of the devices and each and translated into 3 languages. (english, french, german). the explanations are simple and can be understood even by a young audience. many games and experiences are available for self-made throughout the visit. the animation around static electricity is well done and generally delights children. there is also the "nostalgia" part in which we can find the household appliances of our youth, that of our parents, or even our grandparents. the setting is warm, informative and entertaining. the museum is quite well done in all. it provides useful knowledge about electricity.

explanation: