A party at a restaurant is super easy to host. Arrange in advance to have pretty flowers or something else decorative on the tables. Talk to the owner or manager about the menu for the party and also decide on a fun dessert or arrange to have them serve a cake that you bring in yourself.
The invitation should include all the details:
who the party is for
that this is for a Bridal Shower
when it will be
where it will be
who is hosting
how to reply and by when - this can be by phone or email
optional: where the bride is registered and a theme for the party
Send the invitations out 3 to 4 weeks in advance and have guests reply by 1 week before the party so you can finalize your arrangements.