The correct spelling is criticism.
Of the two, I feel that the first is best. The white background of the second signature makes me feel as though I am looking at a photo negative; the contrasting colors are too much.
The font that you used is rather bland – perhaps you should visit a website such as dafont.com and download a few, more original fonts. I adore the color technique that you used with the font (from black to white when necessary in order to see the font against the background), however.
Now, for your Selena Gomez signature.
You did brilliantly on matching the contrast of the B&W Selena with your background. Good work.
I don’t know what photo editing system you are using, and therefore, I will not comment too much on the edges of your images – but may I recommend using GIMP, if you aren’t already? With the assistance of tutorials, the system can be quite helpful when blending images.
Conclusion: You did quite well, considering the fact that you only just started making graphics. Keep working on those stubborn edges. They can be quite a pain in the neck...