The picture task is the second part of the oral exam: you pick one of three photos and describe it for about five minutes. The fastest way to get good is to study a full description that scores. Here is one, built on the four-step framework (intro, scan, person, opinion).
The scene: an older couple on a wooden bench in a sunlit autumn park, a big tree with orange leaves on the left, a black lamp post on the right.
Step 1: Intro
Ech gesinn e Bild. D'Bild ass eng Foto. D'Foto ass faarweg. D'Foto ass dobausse gemaach. D'Wieder ass schéin. D'Sonn schéngt an den Himmel ass blo.
Six short sentences set the scene. Open the same way every time and it starts itself.
Step 2: Scan
Am Hannergrond gesinn ech héich Beem. Donieft steet eng Heck. D'Heck ass laang. Lénks steet e Bam. De Bam ass grouss. D'Blieder sinn orange a rout. Riets steet eng Stroosseluucht. D'Stroosseluucht ass aus Metall. An der Mëtt vum Bild ass eng Bänk. D'Bänk ass donkelbrong.
Walk the scene in a fixed order (background, left, right, middle). Name a thing, then add one short fact about it.
Step 3: Person in detail
Op der Bänk sëtzen zwou Persounen. Et sinn eng Fra an e Mann. Si si vläicht fofzeg Joer al. D'Fra huet en helle Pullover un. De Pullover ass rosa. Si huet kuerz Hoer. D'Hoer si brong. D'Fra gesäit roueg aus. De Mann huet eng donkel Jackett un. Hien huet kuerz gro Hoer. D'Fra hält d'Hand vum Mann. Si kucken zesummen no riets.
Pick one or two people and describe them feature by feature: clothes, hair, expression, what they are doing.
Step 4: Opinion
D'Bild weist eng friddlech Situatioun am Park. Ech fannen d'Bild ganz schéin, well d'Faarwe waarm sinn. Et ass e rouegen Hierschtdag. Esou eng Zeen gesäit een dacks an de Lëtzebuerger Parken.
A short close: sum up, give one opinion with well, and link it to everyday life.
That is about 210 words and four to five minutes of speaking, exactly what the task wants. The method behind it is in how to describe a picture.
If the examiner asks a follow-up
Finish early and they may ask Wat maachen d'Leit op dësem Bild? (What are the people doing?), Wéi eng Joreszäit ass et? (What season is it?), or Wou ass dëst Bild gemaach ginn? (Where was it taken?). Answer with the same simple sentences. The only way to make this automatic is reps, so practise on real photos until the four steps run themselves.