Ive been creating websites in html/css and by help of wordpress sometimes. Talking of wordpress templates there are some concepts which i do not grasp.
Wp templates are made of php files and have their own coding like instead of 

```
<a href="#"><img src="/wp-content/minamaze/image/AJTFixPreisBanner.jpg"></a>

```

i have to write following to include an image:

```
<img src="<?php bloginfo('template_url'); ?>/images/AJTFixPreisBanner.jpg"align="middle" />

```

why doesnt simple html code not work and why for example does following tweak of the wp template code not work for me(to center image) ?

```
<img align="middle" src="<?php bloginfo('template_url'); ?>/images/AJTFixPreisBanner.jpg" />

```

Obviously im not that familiar with wp templates codes as i would like to be , is there a comprehensive literature to gain this knowledge (the wordpress codex page is not comprehensive enough imo and at my level