Help with searching for files.

Are there wildcard symbols that I should know about when searching for a file. I type in one word "propane" thinking it will find all files with that word in it but it matches nothing. I'm a PC user for years with an iMac at home and no time to go through long tutorials. The Frustration is overwhelming. The "simple" answers don't seem to talk about the nitty gritty of task--or I just don't know where to look. Thanks for any help you can give me.