> I wanna please him so badly in return and don't know what to do.
And in addition, please read this article listed in
the Index:
How Do I Get Him/Her to Orgasm From a Hand/Blow Job?
> I don't know why it made him sore though...
Possibly technique; possibly timing; possibly both
If your teeth happen to scrape against him, this can be irritable; however, what you are describing seems more likely to be that you begin too early when he is not aroused to a high degree, and/or, that that your technique although not bad is going on too long.
The latter is a discussion you should have with him. You need feedback that only he can provide.
Stimulating the glans of his penis can be done a little bit early on when you first begin foreplay; however, the serious work should wait until you have him near the peak of his arousal curve. Explore and work together on this and ask for his feedback (verbal or non-verbal) on how he is responding to your caresses.