First comics reading: "Superman" in Action Comics #1 (1938)
Here is the epic number where Superman, Clark Kent and Lois Lane appear for the first time. Below the comic book you'll find a link to an online comic book shop where you have the possibility of purchasing a reprinted hard copy of this pdf file. Of course, the original 1938 copy is beyond most people's means as we can see from the first link of the Extra Material. The other two links are the sections of the origin story of Supeman in newspapers and the first comic book bearing his name.
If you are really interested in the stories of the first number of Superman, you should have a look at Superman #1 in the last link of Extra Material. Superman #1 has the beginning and the end of the stories that are included in Action Comics #1, and if you look at these sections closely, you'll notice that these are add-ons to the original story in order to complete it. Nevertheless, for our purposes, Action Comics #1 is enough because we are going to focus on Lois Lane's story.