Help with a sliding menu?

Hey guys!

Just wondering if anyone would know how to help me out with this issue:
I’m trying to get my menu to slide over to the right and reveal some content underneath once clicked (mostly likely will be text and a few photos.) However, I seem to only find help in regards to having the menu slide out from a previously hidden state.

If I’m not being clear, I’ll be sure to add a diagram of what I am trying to achieve. Thanks!