I am shy and need some advice on what to do in this situation ?

I am really shy and I am trying to work on it. I am trying to make friends but my shyness is getting in the way. There is the nice guy that has a lot of the same interests as me . He always says hi and tries to tries to have conversation with me. Everything was going well until he asked me to be in a group project. When the whole group got together I felt a little uncomfortable outside of the school setting. I tried not make eye contact with him and I talked and looked at the other girls in the group because I feel less shy around girls than guys. I was embarred and scared that I would humiliate myself that and didn't want to make it to noticeable that I was just shy. I think he felt like I was not interested in him and maybe that I was mean or maybe unfriendly. The next time we meet him he just wanted to finish the project and left early. We were suppose to meet up again for one more day but he said that since we finished not to meet up again. I feel horrible and I want to talk to him and explain that I am shy and do want to be friends with him but I just don't know what to say or how with out looking like a total idiot or looking way to desperate. What should I say to him and when ? Please help !!