have tested paint colours on white cards , do i need to paint the walls white to get the same colour

[ggirl]

currently the walls as cream

Depends how dark the cream is... Better to test them on the surface you'll be painting....

tried that in splodges around the room and found it so confusing as everywhere it looked different

Should be fine. If your paint is thin enough to see the cream through it you'll be needing 2 coats anyway.

beware of splodges as the thick edges of the shapes will show through, unless you brush them away to nothing.

thanks
it's little greene paint so hopefully not thin , have never used it before