Can You Put Up Posters in Bratz: The Movie (Wii)?

No. Bratz: The Movie (Wii) does not include a poster-placement or room-decorating mechanic.

What the Game Actually Has

• Story Mode: Follow the film plot across 5 chapters.
• Mini-Games: Fashion design (color/pattern matching), pose runway, photography, dancing (Wii Remote gestures).
• Closet / Dress-Up: Mix tops, bottoms, shoes, accessories for each Bratz girl.
• Unlockables: Outfits, photos, video clips — viewed in gallery.

Games With Poster/Room Decoration

• Animal Crossing: New Horizons — Hang posters, photos, wallpaper, flooring.
• The Sims 4 — Build/buy mode: posters, quad posters, custom content.
• MySims (Wii/DS) — Furniture placement, essences, town building.
• Style Savvy / Fashion Dreamer (Switch) — Boutique management, display windows.

If you're stuck on a specific mission — describe it; the solution is likely a mini-game, not decoration.