I want to create an online forum. From my server settings I have two option of smf and phpbb. I hate both of them!. Is there any solution to turn the wordpress to a full blown online forum?
bbPress might be what you're after. It's a forum plugin written by the creators of WordPress. You can learn more about the plugin at its site, or look at the plugin page at WordPress.org to learn more. I've used it for simple forum purposes, and its worked quite well.
I would recommend it over Simple:Press if you're looking for something easy to use, theme, and change. The name aside, Simple:Press is quite large and even had its own plugin system (you have plugins for a plugin, which is weird). Also, as far as I could tell, you needed to pay to read the Simple:Press documentation, where the bbPress docs are available freely.
The most widely used forum(ish) solution for WP is http://buddypress.org/
If you just want them to look a like, you could use a custom theme and build key elements so they can be included in each application. I have seen plugins for bridging WP with other forums, but don't know how well they work. If you just want the look to be similar, I wouldn't worry about bridging it.
There are also other forum plugins for WordPress, though none of them really come close to the functionality of SMB or PHPBB. It will boil down to your exact needs. I would try to stick with something as "supported" by WP as possible.