How can I make my website SEO friendly?
Other parts of the website, that are looked on your website by search engines
Joomla System → Global Configuration → Site Name
WordPress Settings → General
Meta descriptions, meta keywords
Joomla System → Global Configuration → Site Meta Description and Site Meta Keywords
WordPress in theme, probably you will have to put this into your theme's files yourself. Look for this code, probably in the header.php file:
Write a description under it, which optimally should be between 150-160 characters, and put the keywords (~230-240 characters) there too:
<head><metaname="description"content="This is an example of a meta description."><metaname="keywords"content="Example,Nextend,Slider">
Joomla System → Global Configuration → Search Engine Friendly URLs
WordPress Settings → Permalinks
For your other images too, not just for the Smart Slider.
To your website from other websites
It's important too, how "popular" your website is. If you can, then exchange links with other websites.
Things to avoid
Don't try to fool the users
If you have a website with a certain subject, then don't try to use popular keywords, that has nothing to do with your content, just to get people to your website, because it will have a negative effect on your ranking.
There are no links to a certain page
Make sure, that you have links to every page, that you have
From any page of your website the users should be able to go to every other page. If you are not using a page anymore, then delete it, if you won't need it anymore. This is for the same reason, as the previous one, that search engines doesn't like, when there are hidden content in the websites, that can mislead people.
Multiple copies of a page
Don't create multiple copies of a page under different URLs
If you want have your page in multiple places, then link the same page to everywhere, don't duplicate it, and use the copies.
Don't be impatient
It could take months to get into search engines.
Social activity, social shares, especially with Google+
Website performance, have a mobile-optimized website. You can read about how you can increase your website's speed in here.