I wanted to make a bottle with ocean in it that is on the table in a sunny day.
Pictures were different dimentions and I think that made picture in some parts sharper and in some blury.
How can I fix this problem with difference in sizes? Can I do anything?
Here is the picture that I made:
Now it looks like Coke,not like ocean
Seems you need to get a higher res ocean pic.
Also, the perspective angle of your cup doesn't quite match the deck it's sitting on, and you will need to add the shadow that the cup would cast on the deck.
Maybe make the cup a bit larger to emphasise the effect.