I created an offline Monero wallet with https://moneroaddress.org/, now is there any easy way to check its balance? I used ShapeShift to exchange Bitcoin for Monero and sent it to my public address using the MoneroAddress address generated for me.
If you want to check your balance with an offline wallet that becomes a little difficult. You can take the view only key and generate a watchonly wallet. Optionally, if you have the transaction id, you can check whether funds a user sent in a transaction enter the blockchain using various block explorers. With shapeshift, immediately after the coins are received, a link should have appeared on the next page allowing you to open a block explorer to see the transaction that contains you coins. It does not allow 100% verification however.
First note your viewkey and address.
Then go to your monero directory and type:
./simplewallet --generate-from-view-key yourAddress:yourViewKey:nameOfTheViewOnlyWallet
where yourViewKey is the view key (obviously) and yourAddress the associated address. The last part of the command is the name you want to give to your view only wallet.
Then follow the instructions from the terminal. To see the balance of your portfolio type "refresh" (bitmonerod needs to be synchronized with the network first).
You now have a view only wallet.