Baptisim ???

Can someone please explain to me the etequette for a batism. Eg, what are we supposed to wear, bring, etc

We are not religious so therefore have no idea about what goes on. Are there any rituals we need to know, are we expected to partake in any rituals, etc

The baptism is at 1230pm followed by the 1st birthday party at 130pm

TIA

Is it a Catholic Baptism? If so, I wouldn't worry about taking anything, unless you want to buy a gift of some sort. Most people would do this for a christening, & being a 1st birthday as well I'm assuming you probably will have something anyway. There are some pretty Christening trinket boxes & things out there that you can have engraved if you would like too :)
There shouldn't be any rituals that would include you, unless you are a God parent.
& dress would be basically your Sunday best :) Smart casual I guess. The same as you would wear to a casual wedding ceremony :)
That is for Catholic baptism though, not sure about other religions :)
HTH