Custom Classes : general questions

Aha. Well, thank you for your "constructive reply" that does't help me a lot, but... please... I kindly asked for best practices as it is written on the top of this forum... I know Codeigniter allows a lot of things, but so far as I know, when you install it, you don't have an integrated cms, and even less in Ajax... You need to build everything as you like.

So maybe my question is stupid, or misconceived, but I was just wondering if it is a good practice to create a class to generate specifics html elements and repetitive kind of queries that would be helpful for building my cms. Or, the good practice is to create everything in controllers for adding specifics html and queries ?