Digital art.. is not something that can be mastered easily. <img src="{SMILIES_PATH}/icon_cry.gif" alt=":cry:" title="Crying or Very Sad">
It takes a huge amount of time and effort to develop a skill in that field, and that cannot be done fast.
There are a lot of good tutorials available on the Internet, but you need to find the one that's suitable for absolute beginners.
Pixel editing is not something I would recommend for any novice learners in art to venture into, as its workload can quickly turn in to a nightmare.
I would recommend the learners to learn how to draw with a pencil first, before considering to draw anything with computer applications.
Even after learning how to draw with graphical applications, it takes a large amount of work to learn more applications to master the game development mastery.
Construct 2 saves time and effort in that matter, because we don't need to learn programming languages.
So my advice for you is to research and find the best graphical application for your need, learn to draw, learn to use the application and voila! <img src="{SMILIES_PATH}/icon_mrgreen.gif" alt=":mrgreen:" title="Mr. Green">
That's that.. and.. for this example, I'll briefly explain what I would do in order to modify the animation.
First of all, you need an application to modify the image files.
I use a Photoshop but other applications are ok as well.
You need to divide the image file into multiple parts so that they can be modified separately.
Here's an example.
Here's a PSD file for that.
https://www.dropbox.com/s/jgorssy35rjnhn8/Lion.psd?dl=0
Then you need to save each part of the image as separate PNG files and bring it into an animation application.
I use an application called Spriter for my games development.
You then need to use the animation application to modify the animation of your image.
Here's an example.
The lion now has two animations -- Idle and Walking.
Here's the Spriter save file that contains the lion.
https://www.dropbox.com/s/x1gf4rxoo3z1t ... .scml?dl=0
Then you need to export them as PNG and import them into Construct 2.
Here's an example.
Here's a final Construct 2 capx file.
https://www.dropbox.com/s/hmi5sp9y1moz0 ... .capx?dl=0
Use your arrow keys to move the lion.