Load more button for most recent post in category

Hey guys!

I’ve been searching for hours now about a good way of loading in more posts.

In my sidebar I have the five latest posts from a category showing. I only want to show three of them with a “load more” button on the bottom.

My first thought (since i don’t know JS) was to do a display:none on the last two items and then, somehow, make the button add a display:block to the stylesheet.

But that were a dead end because of browser incompability.

Heeelp? ??