After just getting something into orbit (and perhaps a Mun landing), the next big challenge for a new KSP player is how to dock in orbit. Here's a step-by-step illustrated guide for how to do so.
(There are various techniques... and plenty of other guides out there. This is just how I like to do it. I hope you may find it useful.)
(Author's note: Please forgive the out-of-date screenshots. This post is ported from a blog entry I made on an older version of the forum software, back in 2