Levent,
I like the basic design of your site, but I have a few suggestions.
I’d like to see a header at the top of the page, something that announces who you are or that says the site is your personal blog.
I agree with like_a_bauss about your use of the color blue. The blue you’ve selected isn’t particularly easy to read. A much darker blue or another dark color would be better. The blue text on the blue background is especially problematic.
You could try #00008B (DarkBlue), #191970 (MidnightBlue), #483D8B (DarkSlateBlue), or #000080 (Navy) for your text.
If you want to keep the blue background, you could try #F0F8FF (AliceBlue).