Important Note after KlintWeb comment:
You certainly want to do any such changes inside a template override.
Search in this site and also in the web about Joomla Template
Overrides to find out how you can create them.
How to wrap the intro-text inside a link to the article:
In components/com_content/views/category/tmpl/blog_item.php
there is a piece of code:
<?php echo $this->item->introtext; ?>
This one echoes the introtext of the article.
A a few lines below, there is:
<?php if ($params->get('show_readmore') && $this->item->readmore) :
if ($params->get('access-view')) :
$link = JRoute::_(ContentHelperRoute::getArticleRoute($this->item->slug, $this->item->catid, $this->item->language));
else :
$menu = JFactory::getApplication()->getMenu();
$active = $menu->getActive();
$itemId = $active->id;
$link = new JUri(JRoute::_('index.php?option=com_users&view=login&Itemid=' . $itemId, false));
$link->setVar('return', base64_encode(ContentHelperRoute::getArticleRoute($this->item->slug, $this->item->catid, $this->item->language)));
endif; ?>
This one generates the link for the read-more button (if the button is enabled). It also takes into consideration if the content is restricted.
So, now you have all the needed elements to do what you want to do.
Just wrap your intro-text with an <a>
element and use the article link for the href
attribute.
*If you don't have restricted content, then just use:
$link = JRoute::_(ContentHelperRoute::getArticleRoute($this->item->slug, $this->item->catid, $this->item->language));