PHP Drupal kowledge

I think nevets refers to customizing the look of a page or a content type on the website, and at this stage I think you probably don't need it yet. Since you asked, the .tpl file like this page--example.tpl.php and can be a page, a node or a comment and it is normally placed in the template folder of the theme folder. do a search on google for template suggestions or theme suggestions or theme hooks for drupal 7, also so a search for tutorials. I think the same can be achieved with a module, search for custom pages drupal, ask if you find difficulty.
You are wondering whether you need to know php to use drupal? You also showed interest to learn using php with drupal?
You are right drupal has its own way of using php and I was always lazy to start learning until recently and am still learning everyday.
I created over 20 great websites including e-commerce during the past 4 years with drupal and ubercart for myself and for others. I didn't need to create a custom module or add my own php function, except tiny editing - here they call it hook. Few times I made my own themes and you can do the same just by following tutorials - it didn't require PHP knowledge except few entries in few files and the rest is HTML and CSS. I always achieved what I wanted with drupal; every function I needed was most of the time handy and whenever I faced difficulty I found on google useful tutorials and alternatives.
At the beginning expect a bit of learning to get things right like breadcrumbs, page title, webforms, taxonomy, views, boost/varnish etc.
You will be a perfect drupalist if you can make yourself familiar with these modules. Taxonomy and views are major players you only need them if your website needs categories and pages under them.
The community is helpful here, however I found maintainers are sometimes too busy to respond but there are plenty of resources here and in google search. And there is always an alternative; with drupal things can be done in more than one way most of the time.
Relying on drupal and on the inputs of others made my already limited php knowledge deteriorate. I also feel guilty I did not contribute and that's why I'm browsing the drupal website today looking for ways to help.
I have been honest, the business websites I made with drupal and ubercart for myself and for clients are allover the internet generating traffic and making sales with limited php knowledge from my side!
For now, just follow what technonow said. Make sure you always have a backup copy of your database and don't hesitate to experiment. We all learn everyday, yesterday I didn't know we're allowed to sign.
I wish you success with your new website and I assure you that learning drupal is going to be fun and like me and the majority here, you're going to fall in love with a powerful content management system and with your new website!

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