Data entry into plain vanilla Excel

I am doing some volunteer work for a local "social services" type advocacy group. I am a bit familiar with Excel and its spread sheet functions. In other words, I can "cook book" it pretty well. I have seen "snippets" of documentation that lead me to believe that I can set up some data entry screens (forms?) for the clerical staff to use that will feed an Excel spreadsheet with member information (name, address etc.). I am, however, having a heck of a time figuring out where to start. The client, from what I can tell, has a really basic form of Excel. I don't think they have or use Access. Is there some way I can set these folks up with add/modify/delete functions in a screen data entry format? Just point me in the right direction. I can take it from there. Thanks so much.