Before you let people loose on creating blogs on your site, there are various settings that you will want to ensure are set up to your liking.
First of all, you can set up some global settings for the blogs within the following area in your admin cp.
This will then allow you to set up whether or not to allow RSS imports and exports, along with globally switch ratings on and off.
Once you have set the basics up, you can then set up your options on a member group level so allow different levels of member access to do different things. You can access the member groups from Members>Members>Groups. There is more about this in the following guide.
Once you visit the blog tab, you will see something similar to the below, where you can set up what you would like the members of that group to do.