Elder M. Russell Ballard said "May I ask that you join the conversation by participating on the Internet, particularly the New Media, to share the gospel and to explain in simple and clear terms the message of the Restoration." (See video below)
Sharing your testimony or experiences of the Gospel via a blog has three principal benefits:
You increase your faith in the Gospel and stand as a witness of Christ.
You help increase the faith of your readers and may interest some to learn more about the Mormon Church.
You increase the likelihood that individuals searching for information about the Church on the web will be more likely to find fair and accurate information about the Church.