Galleries/functionality

I am new to WordPress (finally) so please forgive my adolescent knowledge here. I have a question regarding a plug-in for a photo gallery. Can someone explain to me how this works in conjunction with a blog. I am told I can get a plug in to have my blog also do a “slide show/website” function like display images in a gallery setting. How does something like that appear on my blog? Is there a link on the header or something typically? Also can it be organized as far as having multiple galleries – i.e. a portrait gallery and a wildlife gallery etc…

Thanks for the help!