Hi Annshouse, welcome to OpenStreetMap. 

To edit the map and see the tags people have added to different objects (roads, for example), you can use the "iD editor" directly on the OpenStreetMap website by clicking "Edit" at the top left. From there, you'll be brought through a guide on how to use the editor. For more info, you can find an OSM beginners guide here: https://wiki.openstreetmap.org/wiki/Beginners'_guide

Regarding your note, it appears you've left this note on Redwing Drive, near the intersection. I find it unlikely that this section of road would have a 5mph speed limit. Did you mean to put this node somewhere else, perhaps the curvy road a few meters north, or the parking lot a little bit south?