In the zip file linked below there is a generic hotspot folder,
There is a file in the folder called ?alogin.html?. There are 2 lines in there one at the top and one at the bottom, that reference www.ispsupplies.com you can change this to whatever but this basically redirects them to that url once they accept the agreement . you can have your website or if its a hotel or resort make it their homepage.
or you can just search replace ispsupplies with whatever
the submit button uses login for guest/guest
to set this up:
Create a hotspot on mikrotik, great a user profile called guest and disable where it says user limit 1 to make it unlimited create a user for hotspot with name guest and password guest and set its profile to guest
delete the hotspot folder in the mikrotik and copy this folder in. and your all set.