About gradients

Hello all!!

How can I add several gradients to a single layer?

I'm trying to do this, I create one gradient and then, when I try to create another, with the same defititions in the same layer, photoshop deletes the last one. Or, worse, it creates a mask to the layer, for ever single new gradient. I'm watching a video tutorial of a guy that does this every time and no mask are needed, but he doesn't explain how to do that.

Could you guys help me?