No problem! Select one of the rewards first, and then add up the total amount of all the rewards you'd like and enter that as the total amount you're going to pledge.
Then come back to the project main page page and click the "Contact Me" button under the "Back this Project" button on the top right side of the page and let us know which combination of rewards you'd like. After we receive your message we'll send you a confirmation and you're all set!
This was accidentally left in the description for the $50 yarn reward; it's just a cut-and-paste error on my part. Once someone has claimed that reward, it's not possible to edit the text, so I apologize for that. Please disregard it.
Don't see the answer to your question? Ask the project creator directly.