Help me please choose right preposition:
Place in container.
Place at container.
When you need to place something inside the container.
I aways have problems with prepositions, can you explain me please, how to use it correctly?
You just answered yourself - inside the container! So, what did you use there? 'in.'
When unsure, look up in some dictionaries. I use OALD, Collins and Cambridge. Check the examples and you'll surely learn it.
A couple for you -