What type of site are you looking to build?
WordPress.com is a pretty powerful tool, they will give you a basic template to work with at a subdomain. (for example instead of beinhasedorim.com you would be beinhasedorim.wordpress.com) WordPress has a lot of add ons as well as basic themes. It is against wordpress’ terms of use for there to be ads on the free version at all.
Prices for upgrades:
Domain: $7.50 a year (beinhasedorim.com) + $12 a year to point it to the wordpress page
To upgrade themes, turn it into a store, or a real enhanced website you would have to host it yourself, this requires paying about $1.99 a month to a provider, and and from there the possibilities are endless…