Just forget about online data entry jobs.
1. You won't be able to find one that's good enough (read genuine)
2. Most are scams, asking you to pay blah registration fees and stuff, and once you do that, you're doomed, so, don't even fall in that trap.
3. Earning money is not that easy as they make you to believe. Even if you land a genuine data entry job, it's excruciatingly tiresome. I've tried data entry jobs two times (offline) and that was actually typing job. They have a number of conditions, most of which are quite hard (not impossible) to fulfil. Most often, they won't pay you citing different excuses like errors/mistakes in your work and such.
4. As someone suggested, starting a blog and putting up ads, it's x times (replace x with whatever number you like) harder than the ease he/she posted that. Ad services don't flock in to put up ads on your blog as soon you create a blog and start posting, neither people run after clicking ads on your blog as soon they land on your blog. Then there are a number of complications involved in earning from ads and there are minimum payout limits too. To really earn from a blog, you need to establish yourself as an authority on the subject matter you choose to blog on. You need to be active on your blog, and be disciplined with your blog and contents, and once you continue to do so, you may expect to earn something, though, this might take more than a couple of years, before you get a good amount of money.
5. Earning from freelancing too is an option, but as long as you're a fresher, you won't be able to land jobs on freelance job portals. No one wants to get their work screwed. If you seriously want to get into freelancing, make yourself competent enough to handle whatever people ask you to do in your domain, and you might end up earning a handsome amount. Same is true for web development. Once you've got a few projects, and you've successfully completed all with the client's complete satisfaction, you can expect to get more offers via word of mouth marketing, but getting those first few projects is a hard thing. You might also be required to offer free help to people who need it, to build a reputation for yourself among your peers or people you know/interact with more often.
I'll suggest, Just concentrate on your studies for now!
In case you want to learn HTML, CSS, I'll suggest starting off with w3schools.com. Their Try out editor is quite helpful to show you instant results sans the clutter in creating html files and saving and running on the browser. I've been using it for quite some time now to learn CSS and PHP. As far as CodeAcademy is concerned, I didn't know of it till now, and the first impressions tell me that this is quite promising too.
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