and how do you find suppliers?
There are two aspects to your question and I can give you some information on both.
1. First of all setting up your online store is basically setting up a website. However having a website is the easy part – its getting people to your website, and not just any old people, but people who want to buy your range of kids clothes. This is the harder part.
However, you should consider "Site Build It" which is now acknowledged as the key way to do just that. They offer not only the web hosting but also the optimizing of your site to get it on the top searches in Google and the other sites. Its a full service for $299 a year. That might sound steep to someone starting up but it is worth every penny which you’ll recoup in spades once your site starts making you serious money. A high number of Site Build It websites get listed in the very top positions in Google etc.
Here’s where you can get free details:
http://www.sitesell.com/stearman.html
2. You need stock. Again, a place on the web that is proving very successful and profitable is Salehoo. Its a complete directory and community of reputable dropship and wholesale companies. A one off payment gets you full access ( dropship is where you make the sale and the item ships direct from the factory/wholesaler – you hold no stock)
Here’s the link
http://www.salehoo.com/?aff=rmc64&type=homepage
I hope these are helpful suggestions. Good luck!