You can earn anything from $5-$500.. it depends on the cpc your site gets, ad placement and many other things..
First you need to focus on getting Real Visitors to your site and no duff traffic through any spammy traffic sites, once you have a boom of traffic hitting your site - as long as it has great content and your adsense is properly targeted to attract a high CTR from your visitors, you could begin earning a few thousand a month. I had a site not long ago that I used specifically for adsense, once I managed to attract 1000's of daily visitors to my blogs, which was my biggest challenge initially, I managed to make about a thousand dollars a week from my adsense blogs alone & its possible for anyone, so I wish you success and remember, FOCUS ON TRAFFIC FIRST then the rest will follow...
First of all, Google Adsense has no issues with using other ads if they are following adsense TOS. For better knowledge you should check adsense FAQ because they can change it any time. Traffic from US, UK have high potential compared to traffic from other countries. Another point you should remember is organic traffic has more potential than referral traffic. In my assumptions (not sure) web design tutorial can earn around $5 per day from 1000 visits from adsense. (Expect less so in reality you can avoid bitter experiences )