Public decks will be visible for all in the list of builds. Private decks will be accessible only via direct link or from your private user profile, they won't appear in search results nor will be indexed by google. Don't be shy, share your decks with others and set visibility to public!
Creating deck/adding heroes:
You can add hero builds to deck by tappng onclicking little "cards" icon near hero build name on hero list page (or on your user page) and then going to deck creation page (bottom right corner after you will add heroes). You can add hero builds to deck in same way, simply select them to be added and edit your deck.
Name and description:
Try to use self-explanatory name of your deck and describe it well, so others will know how to build such a deck.
Options and tags:
Setting Chaos level and/or game type will help players to find your build if they are looking for something specific. Tags will also help others to find your deck and will quickly show for what it is made for.
Stats and shards:
Those are inherited from plugged hero builds, you have to edit every hero build in order to change stats and shards in your deck.