I last played dnd back in 2.0. I am looking to get back into the game. I do not know how online dnd will work out. Any suggestions how i should get started?

Well, generally, you download and install a program like OpenRPG or buy and install one of the for-profit virtual tabletop programs, then start looking around for a game that's recruiting, either by checking the forums or by asking around on the game-servers after booting up OpenRPG or whatever. Not everyone uses the forums, though, so sometimes you have to go looking on the game-servers.

For reference, on OpenRPG, it's generally good etiquette when looking for a game to either ask around in the game-server Lobbies or to enter some of the rooms and use the Whisper option, to send a message to the GM/DM in that room (people with GM status normally have their names listed in red text on the side of the OpenRPG screen, on the Player List frame). It's generally rude to enter a game-room and interrupt it by sending a chat-message to the whole group in there (thus sending a Whisper to just the GM is best, and doesn't interrupt the game for the others with OOC chatter).

If the group hasn't started their game-session yet in there, it's probably okay to just ask the whole room by sending a normal chat-message. Typically, Out-Of-Character chat during a game-session is put into (parentheses) or ((double parentheses)) to separate it from In-Character chat.

Sending a Whisper-message in OpenRPG is just done by right-clicking your mouse cursor on someone's name in the Player List frame, and choosing Whisper, then typing your message and hitting enter. If they reply to you via Whisper, it'll create a new tab along the top of the Chat frame, where you can click to see their reply, and while that tab's active you can type and send further whispers to the same person directly in that whisper-tab.

If your free around 1 pm Eastern time (6 pm GMT), you might take a look at my recruiting thread here, for a 3.5 D&D campaign I'm trying to get players for.