A few problems

[Hunter]

I'm making a map surrounded by walls. But the players are not allowed to walk on the walls. How do I do that??
In my map I'm also making an ocean, but how do I make 'waves' in the water like on Omaha Beach???
Plz help me.

[Surgeon]

(1) in the common textures folder there is a texture called clip - this should prevent the player moving through it. Just place a brush textured with the clip texture over the wall. This will stop players getting on the wall. If the clip texture doesn't work the playerclip texture will.

(2) look in the misc_outside texture folder. In there should several textures staring either with Ocean or DeepBlueSea. Make sure you have both 'Show shader textures' and 'Show non-shader Images' boxes in your preferences ticked.