Inserting audio embed url from my library

I am not technical and have four 3 sec voice files to embed as links (is my wording off?)to a word. So that user can hear the word as it should be pronounced if they want.

I created an audacity mp3 file for each word and uploaded them to my gallery. I am reading that even though I can upload a file to my media library I cant really link or embed it without accessing it via a url from a third party server.

If this is true and I am home can I do this using my server at home or a DropBox server? Just wondering. I will need to do this quite a bit in the future…

Thanks

ps… unrelated to above, but is it true if I modify existing website pages and posts, search engines will always call up the original version of pages and posts?