What are the steps to dev'ing a commerce site?

[franchise]

Need Help dev'ing a commerce site

I'm new to developing sites. Fairly computer literate and working with a mac.

I need to get a site up to sell about 20 items and process credit cards etc. It will be a product that my company manufactures. We will have to deal with all sales and returns via internet and phone. In otherwords, I'm not drop shipping someone elses goods or acting as a portal for a seller.

Could someone outline a step 1 step 2 on how to start?
Do you get the cart first, find hosting first, do you use a free cart (osCommerce) or a pay for cart (x-cart?) etc. etc.

I'm willing to roll up my sleeves. I just need to get a road map. It seems a bit overwhelming with all the choices out there from freeware/open source joomla/ etc. Don't know which way to go and why? i can't seem to visualize the whole process.

If anyone with a good deal of experience could chime in, I would be very much appreciative. Feel free to pm me or just post. This could be a useful thread to other newbs if it hasn't been done already.

Thanks,
N Fran