Hell jactahiti, very pretty image. As far as lens effects goes, the first "effect" I can think of is when you use a perspective camera, set it up like a real camera. Use a real world lens like 50mm in the focal length value, and then turn on Enable Dof. Assign a focus object for your lens, and choose an F-stop, say 2.8. This will then act like a like a real world lens, of course render times will go up.
But for your particular image this is not relevant, as in the real world it would be shot probably at F11 from such a distance Depth of Field isn't relevant. But if you get down into those little huts for more close up shots it could be important.
Here is my 50mm F2.8 Lens, may seem obvious but emulating a real lens that you would use in the real world to photograph or render something is very important in my opinion.

- cameraSettings.jpg (32.63 KiB) Viewed 3449 times
Additionally you can grade your image to give it potentially film like looks via image filters on your render layer which you can see here:

- ImageLayerEffects.jpg (27.36 KiB) Viewed 3449 times
You can also use the Layer Editor to do post processing as you might expect to do in Photoshop. Simply add new color, image or reference layers and apply them with standard overlay types as you would in Photoshop:

- ImageLayerEditor.jpg (28.45 KiB) Viewed 3449 times
Using the Layer Editor you can create a lot of effects. In the following example, I'm referencing in my render layer (Reference Layer type, renamed BLOOM and referencing my 3d render layer named _3dLayer_Shot_001_CG), applying a blur and a contrast and then setting that layer overlay method to "screen" for a bloom effect. Additionally I've put a color layer with a textured multiply filter using a cell texture to create a vignette effect by setting the overlay method to Multiply.
Here is how the layer setup works, easier to see in the Explorer view:

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So as you can see you have a lot of options to manipulate the rendered image. However depending on what you want to do, and weather or not your scene is animated. For still images I would render with a DoF lens and go into Photoshop. For animated sequences I'd be more inclined to manage this entirely in Clarisse.
Hope this gets you started in post processing your images within Clarisse, let us know if you have any more questions.
Thank you and keep up the good work!!!