how am i to make payment through Google Wallet ?
unfortunately, such option is not available right now. All our payments are processed through PayPal, but you can use a wide variety of option to either link your credit/debit cards to PayPal or upload funds through different sources.
Nonetheless, we will consider adding an alternative payment option in the future. You're welcome to add your vote for this request in our Votebox: http://todoist.com/Vote/showProposal/34/