Like Bogey said ... check the W3C Validator ... except that the address is http://validator.w3.org ... your "home" page has got 33 errors on it ... you can click here to see them ...
You could also disable the link of the page that a user is on, for example, if a user is on the "home" page you could disable the "home" link and make it another colour (or rollover state), this way users know which page they are on, and the don't redirect to the page that they are already on ...
The "contact" page looks totally different to the whole theme you've got going on the "home" page, and it doesn't have any navigation buttons, so I can't just go back from there without having to press the "back" button in my browser ... Not good!
Then also, that message validation doesn't work properly ... I just sent you an empty message with a username of 'rt' and an email of 'rt' ... at least check that there is a message, and check that the email looks a bit more valid like checking that it has an at (@) and a dot (.) in and is at least 6 or more letters ...
On your "home" page every article has a nice description (a cut out of the article's text), but on the other pages, like the "Beauty and Fashion" page, there is only a heading ... and on that page there is only one ... it looks way too empty ...
On the "about" page, there is a link that points to the "contact" page ... why does it open in a new window?
And then after reading the text on that page, I realize that you really need someone to spell check your articles after you've written them, because that page (about) is full of gramatical errors ...
On the "advertise with us" page, there is a bold word that says "contact us" ... why isn't that one a link to the "contact us" page aswell, like on the "about us" page ...?
Oh No! That sitemap is straight XML ... what's the use of having that ... please take it away ... That is more like a google sitemap, not one you show your customers ... take out that link immediately ... please ...
For your search box ... I'd switch away from that "search pixie" immediately ... Rather add google search to your site ... it's way better than the one you've got there now ... seriously ...
Then you've got three buttons up top in the "top nav-bar" and five in the left hand side one ... why not put the other two buttons in the top one aswell (Advertise and Sitemap)?
I see in your code you have links to two more stylesheets ... how do I access them? is there a button somewhere to make the theme switch or how does it work?
Okay that's a start ... I've got more to say, but I'll leave it for another day ... lol
Let's leave all our *plum* where it is and go live in the jungle ...