i use an online wallet: ethereum-wallet.net. I heard that online wallets are risky but so far I havent had any problems. Of course if you have a lot of crytptocurrency, you should probably use an offline wallet to be absolutely safe.
You can use an online wallet if you want but you need to be aware of the risks, of using on of those services, since you are part of a big service like that then hackers will sometimes target this websites to try to steal the coins, instead if you use your own desktop wallet then you are a very small target that will not bring too much attention.