2
You can modify anything In Xoops, but how easy it is depends on what you want to modify.
If you want to add additional fields, then that's a bit tricky because you have to create associated database values etc and insert them into your templates. I can't help wit that.
But if you just want to change the layout of what's already there, then you can edit the template for the registration form (not sure of the name but should be in the system templates). If you just want to change the wording, I tend to do a copy and paste of the phrase I want to edit, then use a text Search (Dreamweavers Search & Replace is create for this providing you select 'Source Code' and not 'Text') over your locally stored website folder. Usually the values are either in a Language folder in a file called called main.php of either a module or the main root Language folder. Then just re-word the text between the ' and ' .
Ted