Anyway here it goes:
1- Go to my page (or other Mo-brother or Mo-sister page)
2- Press "Donate to me" or "Donate to my team"
3- Choose the amount: for example: 5.00 (don't forget to add the '.00' otherwise you will get an error)
4- Enter your card details.
5- Enter your billing address.
6- Press continue
7- Press Process payment. And confirm by pressing "OK".
8- Add a message or select the box that will make your donation and message private.
9- And then choose "Submit Message and Collect Receipt" or "Skip And Collect Receipt".
And that's all! =)