how can i connect my powerbeats to my watch 3

Hi

When pairing Powerbeats3 with your iPhone, they are also automatically set up with your Apple Watch.

More information and instructions:

Set up and use your Powerbeats3 Wireless Earphones

Instructions for pairing Powerbeats2 earphones to Apple Watch are provided here:

• Bluetooth Basics—Powerbeats2 Wireless
• Use Bluetooth accessories with your Apple Watch - Apple Support

More information:

Listen to music on your Apple Watch - Apple Support