With the wonders of online publishing staring in everybody’s face for hours each day, the traditional broadcast and print advertising is fast receding. Even mobile phone ads and tablets are catching on rapidly for sheer accessibility and portability on the go and in remote places too. Besides, there is really no need to advertise separately online. Websites nowadays of assorted look and feel on a broad spectrum of subjects simply incorporate the little text based or pictorial ads around the page similar to newspaper formats.
A little common sense and we get the hang of it. Website content and ads need to be related, though. If the website deals with amazing tourist attractions, include ads about hotels and travel facilities, things to do and sightseeing tours. A website about fishing could include ads for the purchase of fishing rods and bait.
Leave the technicalities to the professionals. The idea is basically quite simple though viewership takes the time to grow. Google is certainly the biggest fish in that online ocean and their invention called AdSense enables the placement of ads. That matching of content to the ad is also undertaken by them but you could make such decisions too.