I want to know from where i can buy a domain name and what i should look for when buying a domain ?
Godaddy.
Look for words relevant to the type of website you're looking to build. For instance registering "hairy-bungholes.com" would probably be a bad idea if you're looking to start a legal FAQ website.
Think about where you anticipate traffic to the website comming from. If you anticipate this being something that people will pass around by word of mouth, aim for a short domain name. If it's something that's probably only going to be visited by people sitting at home on their computer after searching for hours online, the length of the domain name doesn't matter as much because they're just going to end up clicking it anyway.
Make sure you look at your name from multiple angles before actually registering it. You don't want to end up being the next "ExpertSexChange.com" (experts exchange) or "PenisLand.com" (pen island). Adding a hyphen between two words (such as experts exchange did) will help if your audience comes mostly from searches, but can complicate the spreading via word of mouth.
If you guys have any suggestions from where to buy a Domain, Let me know.
Godaddy.
Also, What sort of websites earn alot on Google Adsense?
You're going to get a LOT of crappy answers to this question anywhere you go.
Reason being nobody wants more competition and telling you what they're doing would mean more competition.
Most of the stuff you hear about is going to be filled with soo many competitors you'll not be able to sleep at night in fear that someone is sabatoging your website to get an edge in the search engine rankings.
Bottom line, trust nobodys answer to that question, not even mine. Do your own research about what people are searching for and draw your own conclusions about how much money there is to be made from the topic.
And do you need to know some sort of programming skills to build up a website to earn money for Adsense ?
You don't need programming skills.
They're useful though.
Also how much money would it take to run a website? Per month?
Taking into consideration maybe $15 to register a domain for the year, less than $10 a month for shared hosting to get started on a simple static content site. Once the site starts slowing down from heavy usage you should be making enough to explore other options such as VPS/Dedicated.
Strong with this one, the sudo is.