how hard is it to create a form of sorts with html that will create some sort of form whereby people can leave messages (it can be anonymous) and can view elder messages left? does anyone know of any free services that could help me with this?
You can't do this with just HTML, you need some database and dynamic language to implement this. I'm sure there is some free script like this (a guestbook?) that will work just fine for you.
you have to use database in that or use it in file system fopen() fclose() in PHP for example see the php reference for that or ask for programming it'll not cost you much cause it's only a snippet of code