you're thinking way too far a head in the scheme of things
first thing you should do is nail down a story line and characters, choose a layout for your comic, then work up a back log of comics for at least 1 or 2 months so that you can post comics at regular intervals so your followers don't lose interest with lack of updates. this also allows you to work on new comics while you're posting the ones you've already made.
Then get your own website. If you do get a website, it is best to pay for it on your own with your own domain name, so that it looks professional, people aren't going to take you seriously, or remember your URL if its something like Blablahblah.myfreehostingsite.com. Basic hosting packages for when you're starting out are pretty cheap, 9 to 10 dollars for a year on some hosting sites, and domain registration is about the same. If you get popular, and you need more bandwidth, you can always upgrade your package later on.
Stay away from ads when you're first starting out. People might be turned off if they come to your comic and get bombarded by ads and think you're just out to make money.
Then choose your medium, best bet for starting out is doing a webcomic, there is a free comic theme for wordpress called comicpress (ComicPress - The WordPress Comic Publishing Theme).