Invitations- I got a template of google by searching "WipeOut Party Invites" There is plenty more so try searching it up.
Another one is try using a program like Microsoft Word. Create a blank white square. Use the Fill in tool and make it a water blue. Create a red circle and put it on the inside of the blue square. Put your info on the inside of the red circle and try and make the blue part look like 'Splashing Water'.