Bottoms up!干杯!
A: This is a toast for good luck. Bottoms up!
祝大家好运，干杯！
B: Yeah, good luck, everyone!
对，祝大家好运！

I'd like to propose I make a toast to....(为...)干杯。
A: I'd like to propose a toast to the newly married couple.
我要向新婚夫妇敬酒。
B: Good luck with your marriage. You will need it!
祝你们婚姻幸福！