I have just donated using PayPal without any problems.
There is a help screen while going through the process with information on the Good Card so I have pasted the information below for those that require it. (My Mum 80 and Dad 79 would never dream of having a credit card :))
More info and FAQ's once you start donating.
Cheers
Gabriele
How does a Good Card work?
What It Is:
The Good Card is a gift card for charity where the recipient gets to donate to their charity of choice. Everyone has their favorite charities and now you can give them the perfect gift - a donation to their favorite charity.

History Leukoplakia bx 8/2006 SCC floor mouth T3N0M0- Verrucous Carcinoma.
14 hour 0p SCC-Right ND/excision/marginal mandibulectomy 9/2006, 4 teeth removed, flap from wrist, trach-ng 6 days- no chemo/rad.
6 ops and debulking (flap/tongue join) + bx's 2006-2012.
bx Jan 2012 Hyperkeratosis-Epithelial Dysplasia
24cm GIST tumour removed 8/2013. Indefinite Oral Chemo.

1/31/16 passed away peacefully surrounded by family