Formatting Help with New-UDNivoChart

I am having a very difficult time trying to format a Heatmap.

Specifically, I would like to explicitly set cell color. I have tried to specify this as part of the data set as per Nivo Website examples. Nivo examples shows that ‘Color’ is appended to the key field in the dataset like this:
@{ ‘Key’ = val; ‘KeyColor’ = ‘Green’ }

Also with the Heatmap, I am not sure how to set legends or titles. Any help is greatly apreciated