craftgrrl | T-shirt Reconstruction Boo-boo

A friend gave me a large T-shirt from her college's radio station. It was neat so I decided to reconstruct it. I had never reconstructed a shirt before. But I was a dork and didn't look at tutorials and did it on the fly. I cut the two halves of the shirt apart and cut the sleeves off. Oh, they're too big for my arms. I'll reattach them later.

I should not have cut the sleeves off.

Now, I have something approximating a tank top in one hand and the sleeves in the other. I would like to
a) reattach the sleeves and
b) make them cap sleeves.

How can I do this?