On a Surface On tells us that the following noun is located on a surface. Use on when one thing is attatched to or touching somthing.
Preposition of Place 'in'
In an Enclosed Space In tells us the noun is in an enclosed space (surround or closed off on all sides). Basically, when something is inside something.
Preposition of Place 'at'
We use at in many common phrases, especially when we are talking about a place for a specific activity.
All walks of life
'All walks of life means' = people from all layers of the society, rich, poor, with various levels of social position or achievement, as a matter of fact, from everywhere!
Talk the talk and walk the walk
If you say that someone talks the talk but does not walk the walk, you mean that they do not act in a way that agrees with the things they say.