Histogram evolution: visualize how a distribution of values changes over time (via) has the article URL slug of 'grafana histogram howto', and the slug is quite accurate. It's a step by step walkthrough of how to do this for a native Prometheus counter histogram metric, which most of them are. It includes copious screenshots, which is especially useful since you have to do all of this through Grafana's GUI and describing GUI actions in text is not necessarily ideal. I've slogged through heatmaps and histograms in Prometheus and Grafana, and this article still taught me something quite useful that I hadn't realized (the 'exclude zeros' setting; I agree with the author that this should be the Grafana default).

PS: Contrary to what the article suggests, heatmap legends aren't always useful, at least in current versions of Grafana. I tried putting a legend on some disk IO latency heatmaps that have very small latencies and the result was not all that readable or clear.