For dApps that have already integrated EIP6963 standard you may choose Wigwam in the list of proposed wallets, when you click the Login/Connect button (Example is the Debank dApp).

For other dApps you should check that you have turned on the Metamask Compatible mode in the Wigwam wallet.

Click Connect via Metamask on the dApp page and confirm connection in Wigwam. 

That's all. Enjoy your work with dApps.