ook i was able to sign my wallet
i downloaded windows wallet
opened wallet
file -- sign message
in the new window i paste receiving address (you can get it when u open your windows wallet click recieve tab then request payment, it ll give you receiving address coppy it)
after i paste receiving address write AIRDROP to middle and go down and click to sign message
it ll give you a signed message

copy your receivng address and signed message and paste to  a text document
add "AIRDROP" end of your signed message that u pasted to text document

go to the bitcore website to register and paste your recieving address
then PASTE YOU signed message to below SIDE ending with "AIRDROP"
 click register, get a success message

if not try from begining again
i did second attempt