I want to learn to program website templates, any tips?
That’s quite an open-ended request. I think you need to be more specific.
‘I want to be a surgeon. Any tips?’
See what I mean?
Programing? As in writing code?
If so, have you mastered HTML and CSS. If not, you’ll need to.
Which CMS platform did you have in mind? WordPress, Joomla, Drupal, Magento, etc.? They’re all a bit different, but you’ll still need to know the languages I already mentioned.
You can’t even start coding a template until you’ve mastered HTML and CSS and a bit of PHP, so I’d start there. It’s not common to code a template from scratch since that would be reinventing the wheel. It’s more common to start out with a good opensource template, like one that WordPress or Joomla supplies, and start designing and coding from there.
There are also various frameworks and site-building tools you can work within for each CMS platform, but that’s for down the road.
Or maybe you’re just considering designing websites by modifying existing already-coded templates? If so, that’s a bit easier, but it’s not what you asked about.