Hiya puppies, that's incredibly kind of you. I'm afraid I only have a Windows laptop. I've bought a small amount of Steem and I'm happy with that for now. Thank you so much for your offer to help!
If you change your mind it should be pretty easy to get you up and running in a secure way. If you pick an existing bts public key from your bts wallet, all you need to do is to give that public key to someone running the steem cli that can register that account for you. I think it requires 100 steem to be vested in the account, and they should be able to register the account by replacing the BTS at the beginning with STM.
From there you can export the private key from the bts gui and import it into the steem webwallet. You will be able to transfer, transfer to vesting, and withdraw from vesting all from the steem webwallet. If your goal is to purchase steem, transfer to your wallet and vest, then that should be well served by this method.