Blow job trouble.

So me and my SO have been together for 2 months, we have amazing sexual energy. My so has even been able to make me cum with out touching me. We have a marvellous relationship and are so in love. My SO has  gone down on me and makes me cum repeatedly. 
But I want to give him a blow job. I've never done it before ever and he is the first guy I've been with. I'm so nervous on how to do it. Any tips?