Question: We know through [General Relativity](http://en.wikipedia.org/wiki/General_relativity) (GR) that matter curves spacetime (ST) like a "ball curves a trampoline" but then how energy curves spacetime? Is it just like matter curvature of ST?

Answer: 
Theoretical viewpoint:
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Einstein field equations can be written in the form: $$\color{blue}{G\_{\mu\nu}}=\color{red}{\frac{8\pi G}{c^{4}}} \color{darkgreen}{T\_{\mu\nu}}$$
We can write in simple terms: $$\rm \color{blue}{Space-time \,\,geometry}=\color{red}{const.}\,\,\color{darkgreen}{Material \,\,objects}.$$
And the $T\_{\mu\nu}$ is a mathematical object (a tensor to be precise) which describes material bodies. In that mathematical object, there are some parameters such as the density, the momentum, mass-energy... etc. So it is those parameters that determine 'how much space-time curvature' is around a body. And one of the parameters is of course *energy*. Therefore, *energy* do bend space-time.

Experiments that confirm this point:
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First, do photons have mass? The answer is an emphatic **'no'**. The momentum of a photon is $p=\frac{hf}c$, and from special relativity: $$\begin{align}E=\sqrt{(mc^2)^2+(pc)^2}&\iff E^2=(mc^2)^2+(pc)^2\\&\iff E^2-(pc)^2=(mc^2)^2\\ \end{align}.$$
The energy of a photon is: $E=hf$ which is an experimental fact. It can also be expressed as $E=pc$ since $E=hf=\frac{hf}{c}\cdot c=pc.$ Therefore, $E^2=(pc)^2$ and so $E^2-(pc)^2=0$. Putting this in our previous derivation we get: $E^2-(pc)^2=(mc^2)^2=0$. Since $c^2$ is a constant, then $m=0$. Therefore, photons have no rest mass.

**Claim:** Photons are not subject to gravitational attraction since they have no rest mass.

**Experimental disproof:** [Gravitational lensing](http://en.wikipedia.org/wiki/Gravitational_lens):   

 ![copyright to the author](https://i.stack.imgur.com/exReS.jpg)

You could see light being bent due to the presence of a strong gravitational field. 

**Conclusion:** Even if light has no rest mass, it has energy and momentum. And it is being attracted due to gravity, so the natural conclusion is that energy do curve space-time.
Matter curves the spacetime because (experimentally verified and mathematically natural) Einstein's equations that govern the spacetime curvature say that the local-curvature-encoding Einstein tensor $G\_{\mu\nu}$ is proportional to the stress-energy $T\_{\mu\nu}$. The latter contains numbers, especially the density of mass-energy and momentum and their flux (which also depends on the local pressure).

Because matter carries mass-energy, it makes spacetime warp. Any other form of mass-energy will do the same thing. I say mass-energy because in the context of relativity, mass and energy are really the same thing due to the well-known formula of special relativity, $E=mc^2$, which says that one unit (e.g. kilogram) of (relativistic) mass is equivalent to $c^2$ units (joules) of energy. 

Mass or energy may be stored in various forms but they ultimately have the very same impact on the spacetime curvature (and other things). Some of the forms of mass-energy look more like mass, other looks like what we used to call energy but there's only one type of quantity that curves the spacetime and one quantity that is conserved.