Buy a quality set of beads (blowfish.com for example carries them).
Toy usage during sex requires the ability to interrupt the love making w/o losing the moment. I suggest you have your partner insert them during the prelimianries--when he is good and stiff and your are turned on.
A latex glove and a tube of lube is needed. He works a well-lubed finger inside your anus to both grease it and lossen it. Then the beads are inserted--they shouldn't hurt going in, just feel weird. Once all are inside, the glove comes off, you turn over and the both of you continue lovemaking. On a towel.
At or near the point of your cllmax the beads are pulled out. For the first time, you should do it so you can control the speed and ease.