Siméon likes to have picnic with his friends.
You usually have picnic somewhere outdoors, in the park, in the nature, in the countryside…
Take care of the contractions with *à* and the articles.
CAMPAGNE (countryside) is feminine singular, la campagne.
There is no contraction with the article LA , therefore: à la campagne.

Siméon aime aller à la campagne.

Yvette adores to eat.
She likes going to a restaurant.
RESTAURANT is masculine singular, LE.
The contraction between À and LE will give us AU.

Elle aime aller au restaurant.

Angélique and Matthieu like to play baseball.
They like to go to a baseball stadium.
Stadium – LE STADE, m.sg.
À + LE STADE = AU STADE

Ils aiment aller au stade de base-ball.

They adore watching movies.
They like to go to a cinema.
LE CINÉMA, m.sg.
À + LE = AU

Ils aiment aller au cinéma.

Mariama likes to read novels.
She likes going to a library.
LA BIBLIOTHÈQUE in French is feminine singular.
There is no contraction with definite feminine article LA.
Therefore: à la bibliothèque..

Elle aime aller à la bibliothèque.

Célestine adores shopping. She must adore going to a shopping mall. Shopping mall – centre commercial, m.sg. (le centre commercial) À + LE = AU

Elle aime aller au centre commercial.