Hi I'm trying to start a small business from home selling baby clothes and acssesories,just selling on eBay at first I have found a few wholesalers, haven't ordered yet its just to make a little extra money but don't have any idea,do I have to register as a business before I order and how do I order.thanks

It is all up to the company you buy from, many will want a sale tax number if you are not going to pay sales tax on the items you buy.
And of course depending on states, you are suppose to be charging tax for purchases made within your own state.

Some may require you to have a business license before they will sell to you. Others will not.

So you need to ask this question to the people you want to buy from. Also ask if they have any mim orders ( or first order) I know the company I work for, we buy from several sourses, from some pricing varies by amount you buy, others require 1000 or so min orders and so on.