I am in charge of a GIS project for an internship I am doing this summer. I have taken a few GIS classes but by no means am I an expert, and no one in the office knows much about GIS. I have to map the locations of their projects, most of which have been in Colorado. I have the specific addresses for most of the projects as well as the counties. What would be the best way to go about this? I have added the USA state boundaries and the USA counties layers, but I am having difficulty joining the excel sheet with the information about the projects to the county layer. Using the specific address would be a better representation of the projects, but I don't know how to do that from scratch. Any tips would be greatly appreciated!