The brightness on your render seems a bit too high so you can barely see the shadows and the creases on the character.
Lighting
The lighting is a bit too plain, I do realise that this is your first render so I would recommend on watching online tutorials on how you could perhaps make the lighting a but warmer or softer and etc
Conclusion
Overall, I personally think that this is pretty good for a fist time render, I would recommend watching variety of tutorials on youtube or other websites on how you could make your render even better.
Looks a bit… plain. I am no expert in this kind of graphic design, but I would make the character doing a pose, I would also make the lighting look more realistic. In conclusion, keep on trying you’ll get better over time! amusing beat me to it
Wow! This is pretty good for a first timer. However, I feel that you should not draw across the render with the red lines like that. It makes the render look very sloppy. For the NPC itself, you should play with the lighting in blender, like what @martxn said.
No offense, but this is far from what a render should look like. I know you downloaded blender yesterday, but the least you can do is rig the guy in a position, add better lights instead of just a sun lamp, and add the poor man clothes…
One way you could improve the render is by adding some type of ground (some place for shadows to stand out), so that the picture can express itself more as if it was a real photograph. Overall a great first ROBLOX render. Can not wait to see what you will make in the future.