fr0sty was definitely not tactful, but his commands are correct. Merge always brings the branch you specify onto the commit you are currently on. The branch command either lists branches (when no other arguments, only certain options, are specified) or creates branches. Checkout is the command used to move around between commits in your repository.

Branching and merging is covered pretty well by Pro Git[1]

[1] http://progit.org/book/ch3-2.html