What is this website about ? Is it about selling cakes ?Is it a dangerous website containt virus,spyware...? No no of course not !So why do you have to submit your blog to all the search engines?
This problem is very very important for advertise blog(Google Adsense, Adbrite,Bidvertiser...). The appearance of your blog at all the search engines can improve your rank in famous services ( Google, Yahoo, Alexa..),increase amount of traffic.This is called SEO.However,the world does not have only these 300 search engines,so you have to find out more search engines and submit to them as much as possible.
However , the famous search engines as Google , Yahoo,Alexa,MSN... You cannot submit by this way, so go to here to see the instructions.