Click on the lightning bolt (screenshot#1)... it will open whatever lightning wallet you have installed & copy in a payment invoice.
I've set mine up to automatically give me a few options (screenshot#2)
Discussion
So how do you set up multiple zap amounts?
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Do a "long press" on the lightning bolt. It opens up a box where you can set up multiple amounts as options and "add"... then select "save" and it's ready for use. See screenshot below.