I recntly bought a knife http://www.wellberghome.com/index.php?c=content&a=show&id=394 the thing is it's heavy a bit and not much sharp in front eventhough it's weight helps easy cutting i cannot make precision cuts how to use these kind of knives.
First: This does not look like a very good knife - this style of secondary bevel (an european style knife usually should not have one, and if it has, it should be more acute) and the fact no exact steel and hardness data is mentioned (eg "1.4116 steel at 55-56 Rockwell C") corroborate that impression.
Very few knives are properly sharpened out of the package. Cheap knives ($20 and below) are not because the manufacturer does not care, expensive ones (>>50$) are not because the user is expected to know how to sharpen it -or have it sharpened- to his preference anyway. Either they are rather dull from the start, or sharpened in a faulty manner which quickly leads to losing most of the sharpness.
It might also be possible that the knife is sharp but needs its edge realigned (using a honing steel or some kind of strop).
However, do not mix up sharpness (test this by trying to slice into a sponge - can you?) with cutting ability (how far can you go through a fridge cold, large carrot before you end up axing it in half instead of cutting it?).
When it comes to precisely cutting: If you are not already doing so, use a pinch grip - thumb and pointer pinching the blade a cm away from where it enters the handle, remaining three fingers cradled under the handle. Mentally focus on where the EDGE is, not the spine of the knife. Use a claw grip, or CAREFULLY guide the blade on the side of some finger of your holding hand, to guide the blade. Use whatever cutting technique you normally prefer, eg rocking cut , or push cut/pull cut/chop, or guilloutine&glide. This knife looks like it is optimized for the rocking cut. If using it, be extra careful not to lift the blade above your guiding hand/finger - you can cut yourself that way.
To give a bit more explanation on the techniques mentioned: Rocking cut is what you often see in households. Tip is resting on the board, knife is brought down like a lever. Guilloutine&glide is the french style that starts with a rocking cut but slides the knife forward after the tip connects instead of just pushing down. Push cuts, pull cuts, chops use only your wrist as a reference point; the knife is completely lifted off the board and brought down while moving it towards you (pull), away from you (push), or almost or entirely straight down (with some momentum). The force dynamics are very different for push vs pull vs chop, giving very different behaviour on tough/hard/soft/brittle ingredients. All these can be done with different sections (heel, middle, tip) of the knife. These techniques are more often seen with asian or modern western cooks, and while they look the simplest, they are the hardest to learn to do well, and they need a sharper knife since there is far less leverage you can use. A somewhat special method is a pure draw slice with the tip being dragged backwards over the board and through the ingredients. Good for elegantly cutting herbs, and clumsily cutting into your finger.