Terrain problems

how do u use multiple terrain types on one map
like ruins terrain next to dungeon terrain
also how do i make it so that the ground is same level as shallow water so you can walk into the water, I can only make it with like cliffs so you cant walk into the water

I don't have WE here, so I can't answer you specifically, but under one of the menus there should be an Advanced> option which allows you to define a Custom tileset. Then, choose the base tileset (which dictates your cliff types) and remove and insert the tiles as you desire.

As far as smooth water entrances, there are two methods.
Either make everything shallow water and raise some terrain until it comes out of the water, or make single cliffs around your body of water and use the slope/ramp/whatever feature to make a path down into the water.