Not bad
This particular song is taken from the Basshunter FL Studio tutorial on Youtube. I know, I've downloaded it myself and gone through the tutorial.
For a first piece, this isn't bad. However, I would suggest playing around with the synths more. Also if you look around you can download extra VST's and plugins like Nexus, Vanguard, V-station and others. This will give you a much wider selection of pre-made synths, and also I would encourage you to play with the parameters to program your own synths.
A little bit of reverb on your synths in the FX rack will help, as they currently seem blocky or chunky. The bassline is alright. The undertone could be a little smoother, and the lead I would suggest trying something like Sytrus to find a good lead. As for your drums you have, they are alright, but a little bit of effects, or searching around for more drum samples will help get a better quality of drum.
Overall, this is a good practice piece. I would recommend taking the ideas in the melody and undertones and try to expand on them before calling it a real remix. I hope this is some help. Feel free to PM me if you would like to talk more. I'm always glad to help.