Help for a newbie

I’m attempting to use WordPress to set up a web site for my son’s scout troop. It will be mostly static pages for the public. Member login and with the ability for a select few to upload documents. Members of the troop could comment on some items and access member only information.

Perusing through all the themes, widgets, plugins, and such available is daunting, especially for a newbie. I’m hoping to get some advice to narrow the search and selection. I’d like side tabs and maybe top ones to link to public pages off the home page. A “log in” button for members. The ability to have some posts, like newly uploaded outing bulletins, appear as links on the home page, “What’s new” perhaps or “Latest outing Bulletin” link.
Something like this, http://lakewashingtonrowing.com/ perhaps. tabs atop and a sidebar. And a photo where the blue wordpress default theme shows up.

What do you recommend?