Getting into DDO is easy. Go to the website
and create an account. Afterward, it should take you to a page to download the game, but if that doesn't work for some reason, you can go here
The download comes in two flavors, standard and high resolution. The high res version looks much prettier, but is also a slightly larger download. Also, whenever they update the game (3 - 6 major updates per year) the high res update tends to be a bit bigger. On the other hand, ever major update has also made improvements on textures and graphics, even on old areas. I like the high res version, but I'm also a graphics whore, so...your mileage may vary.
Once you're into the game, hopefully things are fairly self explanatory. When you make a character you can pick to go with a specific build/concept or you can customize the charrie. The actual customization of your toon is one of the last steps in the process.
In regards to TP (Turbine Points), you get some points for free by playing the game. Each quest/adventure awards a certain amount of favor with various groups. When your total reaches certain benchmarks, you get a number of TP. The favor awarded for a quest varies based on what difficulty it's done at and the base value of the quest, but runs anywhere from 2 or 3 for a basic quest on easy to 12 points for harder quests done on Elite. You earn 25 TP every time your Favor total hits a multiple of 100, as well as certain threshholds for the first time on a server.
In the end, it's possible to grind for favor and never have to buy TP. On the other hand, if you ever buy TP, even the minimum amount, you get certain advantages in perpetuity, such as 4 character slots rather than 2, drastically increased gold limit (43 million, vs. 12500 at level 1 and doubling each level), unlimited vs limited auctions and so forth. The cheapest TP bundle is currently $6.50.
I would recommend looking at DDOWiki
for details on the game. It might help explain concepts, mechanics or quests if you have problems and nobody else is around that can help. Usually, though, there are some pretty helpful people in the beginning area. If you have an advice question, just type /advice and type what you want to say in the chat box in game. That way the text shows up in the specific advice channel, which should show in your main chat window as a golden/yellow color.
If you have any other questions, just ask ^_^