Webforms has traditionally been the main method for developing templates in Relatude. Many still prefer to use Webforms for new development.
There are no set rules for making templates in Relatude. You have full freedom over the html. You can develop a Relatude template exactly as you would develop a normal aspx page. The only major difference is that you fetch the data you need in the page through the strongly typed data access API (using LINQ or AQL) that is automatically filtered on access rights for the current user.
You can use any type of web control in Relatude templates, including all the built-in controls in ASP.Net as well as any 3rd party control on the market. There is also full support for other features of in .Net like Masterpages, UserControls etc.