Magento is one of the most powerful Ecommerce.Magento is available free and paid.you have to run Own store using free software Download magento community Edition .By Default magento theme display magento Default logo To chnage the magento theme home page default logo to your own store logo image is very simple method.
1)First Copy the your required image and paste that image into yoursite\skin\frontend\default\default\images
(this is default theme root)
2)Go to Magento Admin Pannel System->Configuration->Design,Expand Header Tab and change Logo Image Src as seen below
3)After Changes the Logo Image Src and click Save Config Button as seen below
4)After Refresh Your Home page to display your own store image as seen below