To add a new post in the slider on the homepage, edit the post you want to feature and check the Feature this Post? option.
Insert the embed code in the Embed Video field or Upload a Featured Image to the post.
Go to WPZOOM > Theme Options and from Homepage > Featured Slider menu you can change additional options for the slider
Setting up Page Templates (Blog, Arhives)
To create a page with all your blog posts or archives, navigate to WordPress Dashboard -> Pages -> Add New
Look for the Page Attributes box in the right side, and select Blog or Archives from the Template drop-down.
After you will publish this page, all blog posts will appear in it.
To add widgets in this theme, access Appearance -> Widgets menu, and drag widgets to your widgetized areas to activate them.
Widgets Structure in Demo
Load Default Widgets
From Theme Options you can load automatically default widgets, exactly as in theme demo. All you have to do is to navigate to Theme Options -> Import/Export -> Widgets and click the button Load default widget settings
How do I change summary content (Excerpt) for a post?
On editing page of a post, look for a field called Excerpt. You can add here summaries for your posts each time you want to adjust manually the length of text which appears in Slider, Recent Articles, Post Archives or when you simply want to have a different text than the automatically picked excerpt.
How can I change the number of posts on homepage?
Go to Settings > Reading
Find Blog pages show at most option, and change the number of posts.