A good effort for your first challenge. I see you wore your thickest skin to this challenge. I gave it a 4, which is what I vote on something that shows some knowledge and effort, but is still lacking in a major way. Looking forward to seeing what comes from you after this.
Seems fairly soft and washed out looking, and there is a slight tilt. All easily correctable with some very minor adjustments such as levels, curves, contrast, saturation, & sharpening.
Very good concept here... the light at the end of the tunnel gives a metaphorical meaning to this that I like. A few comments about the photo given to suggest some things I would improve upon if this were my photo. The top edge of the tunnel shows that this needs to be straighened a bit. A degree or two of rotation would help that. Also the shot either isn't sharp or isn't quite focused enough. I think that it isn't sharp and may suffer from camera shake. I would try playing with the contrast a bit to get more contrast and maybe trying a black and white conversion to see what looks better. The arch is a great shape and it does have good depth down the tunnel and texture with the rock face. The rails serve as good leading lines.