The others here have great things to say! I am a Christian married to a non-believer so I know some of what you're going through. If I read right you are a new Christian- praise the Lord! I suggest you pray, submit to your husband- even though he's not a Christian, God gave him to you and wants him to be the leader of your marriage- there is no other way it will work. Right now I tithe on my income only, and after asking him if that was okay. From my understanding, it is more important that you follow your husband's lead than to follow a strict rule of giving 10%. Also, giving is not only about money. Find other creative ways to give of yourself and with a cheerful spirit and you will be rewarded.
I also suggest you read this book- When He Doesn't Believe by Nancy Kennedy. It is so helpful, I really, really hope and pray that you'll read it! Find others in your church that have non-believing husbands and pray with them regularly. I will be praying for you too. This is hard stuff, but you can pull through with God's help! Please email me if you'd like to talk more! I'd love to help!