I just don't have a URL, the cloud service just is not working for me.
Is there a place where I can upload and sell games?
And if I wanted to make a space shooter game, or a platform game, how many levels would I need to make in order to sell it for around $5 or $10?
On PC's, you could upload and sell your game on sites like itch.io, here in the arcade section (tough I haven't used the scirra arcade) or on Steam, but there it's a bit tougher as you have to pay 100$ (which do go to a charity so thumbs up to them, but is still a pretty hefty sum) and your game then has to be voted by the community trough Steam GreenLight (so it still may not make it on steam...).
If you are making a mobile game, I think Google Play is the best(-ish) place to put your game if you are looking for a big market (but also extremely competitive...) and if you have 25$ to pay the one time entry fee. You could also upload it on other app markets like the Apple AppStore (99$/month fee), Amazon's own AppStore (Haven't used it), Nokia's AppStore (19$/month) or even on some websites for free (but on websites you need to give players an executable file of your game and it's not that great if you want to sell your game).
On consoles it's a bit different due to their closed off echo-system... I haven't published anything to consoles yet, so I can't guide you.
As for how many levels you need to sell a game, I think slapping a "500+ levels!" sticker on the box won't sell your game alone...
A better way to do this would be to look at some great games in the genre you are making your game and see why they did so well, what made them stand out, what they expressed to the player and see what your game can do differently. (I don't play a lot of shooters, but for platformers, look at Limbo, Mario Bros, Snapshot, VVVVVV, Terraria (more or less) and see what made them stand out from the rest)
They all did well because they saw what other companies and games were doing wrong and thought of interesting things to spice things up.
And just because you set out to make a platformer, a shooter or anything else, you should not be afraid to break the genre wall and try something new.
A good story also goes a long way towards selling your game.
5-10$ is a bit much for (what I assume is) your first game. My first game was 1$ on Google Play and it got only a hand full of purchases (I'm not saying it was a great game or anything, but it definitely was way less than what I was expecting =D) Don't set your hopes to high, and don't worry if you don't make it big with your first game! You still have many more to make and experiment with.
Also, as a side note, I'd heavily recommend watching Extra Credits on youtube if you are into game dev and design. They do awesome episodes about games and game design related things!
Anyways, hope this wall of text helped you in some way,