I join in some airdrops,but theres no information about the airdrop giveaway or on the site about adding token and contract info, they just want my eth wallet.Maybe the info will be given after ICO?
At some the cases, there is no information about how to add tokens since it was way common now to others. The information you will see at most of the cases is about when is the distribution period.
Now if you joined an ERC20 tokens airdrop
(the one that required you to give your ETH address to them) and you are aware of the time of distribution or just excited to see your set of tokens list etc. just check your address at etherscan.io or ethplorer. In that way, you don't need to log to your MEW when checking your token list especially if you are expecting an airdrop.
*Take note that not all airdrops are ERC20 tokens.