To put a decoration or an item from the Station to the Storage, you need to do the following:
1) Tap and hold the building until it lights green.
2) Choose the Box icon.
The item will appear in the Shop in the corresponding tab. 
Note that factories and houses for workers can not be put into Storage.
We’ve also prepared a short video guide on our YouTube channel that explains everything visually and makes the topic even clearer. There, you’ll also find more useful videos and fun contests with awesome prizes :)