Just bought some on Bittrex and now I want to send them to my newly created webwallet.
I tried my ID as "adress" at Bittrex and my public key as "message", but it does not work. I also tried just my ID and "Test" as message, didn`t work either.
And then I thought I might just ask here what to do :-)
bittrex is a bit strange, it only accepts to send to "addresses which are known to the network".
you need to make one outgoing transaction from your wallet,
afterwards your public key is known, and the bittrex transfer will probably work.
to have initial funding for that outgoing tx, try the http://faucet.horizonplatform.io
or if that is down, then anyone here can send you 1 HZ.
my manual is here, you want to read the steps (1) to (5)
https://bitcointalksearch.org/topic/how-to-buy-assets-on-horizon-the-complete-process-explained-for-newbies-1006327