Multiple .pdf Pages in 1 file

I have Adobe Photoshop LE and need to scan in about 100 pages. I can save them as a .pdf file and open them in the free Acrobat reader. I would like to save them all as one file so I can page through them. I can only figure out how to save them one page at a time so they would each have to be opened seperately. Am I able to do what I want to do using these programs or is that something I need the Acrobat Writer for? The pages do not need to be edited, it is just a catalog I would like others to be able to look at online or by CD instead of having to print many copies.