Texas Holdem is THE game for beginners and for average poker players alike. A community card variant just like Omaha, Texas Holdem features a much bigger small term variance than any of the other games currently offered by online poker rooms. That makes it the best choice for beginners because due to the high variance, the skill factor will be dampened, at least over the short term. In layman terms: skilled players will have less of an advantage over beginners than in any other poker variant.
The rules of Texas Holdem are easy to learn. It only takes people a few minutes to gain a basic knowledge of the rules and of some basic strategy. Don’t let that deceive you though: Texas Holdem strategy is almost infinitely intricate, and even top players are on a continuous learning curve. The reason why you have to accept the role of a perpetual student is that your actions are measured up against those of other players. Since your opponents and the online poker community in general is continuously evolving too, you’ll have to search for new ways to wring money out of the game all the time.
In order to achieve your goal of getting better and better at Texas Holdem all the time, you have several sources at your disposal: there are Texas Holdem Strategy books and e-books out there, some of which you can purchase for money and some of which are offered for free. There are poker article sites and forums, and of course, poker rooms like Full Tilt Poker, PokerStars, Party Poker and tens of others where you can put in some actual practice.