Most theme questions can be answered by reading the theme documentation. I encourage you to read the documentation if you encounter any questions when using your new theme.
Themes are available from two separate Mojo sites, Mojo Marketplace & Mojo Themes. The answer to some questions may depend on where you purchased from, so please note the distinction when it applies. Also, if you made your theme purchase through your host, then Mojo Marketplace would have been used.
If you purchased from Mojo Marketplace, go to My Account / My Purchases to access your theme files.
If you purchased from Mojo Themes, go to My Account / Buyers / My Downloads to access your theme files.
To upload via the WordPress Theme Uploader, you will need to use the solstice.zip file. If you purchased from Mojo Marketplace, this file is available to download direct from your My Purchases area. If you purchased from Mojo Themes, this file is located inside of the "Solstice - Theme and Documentation.zip" file. Note: Attempting to use the "Solstice - Theme and Documentation" zip file directly will result in a "Missing Style Sheet" error.
In order to install, you must use the solstice.zip file. Attempting to use any other file will result in a "Missing Style Sheet" error.
On some computers, particularly on Macs, when the solstice.zip file is downloaded, it may automatically open. Just look for the folder titled "solstice" and compress/archive/zip it back up.
By default, Solstice will display your latest posts on the homepage. To use the homepage as seen in the demo, click the Add New button to create a new page. Name it either Homepage or Home. Then look in the far right column for the Page Attributes section and select Homepage from the Template drop-down menu.
After creating the new page with the Homepage template, go to Settings / Reading (in the left navigation bar). For Front page displays, choose A static page, and for Front page select the newly created Home page from the drop-down menu. Then click Save Changes.
You can add slides for the homepage slider by adding new posts. Go to Posts / Add New to create a new post. Images for the slides should be entered as a Featured Image, in the bottom-right corner of the screen. The recommended dimensions of the slider image are 960px wide x 540px tall. To enter a Featured Image, click the Set Featured Image link. You can drag and drop your image to the pop-up media uploader or click the Media Library link if you've already added the image to your Media Library. Once your image is selected, click the Set Featured Image button. Depending on whether you are planning on displaying your slides as your most recent blog posts, or from a specific category, you may want to select a Category. Finally, click the Publish button to publish your post.
In order to view slides on your site, you'll need to have a page created with the Homepage page template and assign that page on the Settings / Reading page. See the How do I have a homepage like the demo site? answer for more details on creating your homepage. Once the homepage is properly set up, you can go to Posts in the left menu to add/edit/manage your slider posts.
In order to view the featured pages on the homepage of your site, you'll need to have a page created with the Homepage page template and assign that page on the Settings / Reading page. See the How do I have a homepage like the demo site? answer for more details on creating your homepage. Once the homepage is properly set up, you can go to Appearance / Customize / Homepage to assign your Featured Pages.
For additional information, be sure to check out the theme documentation: