It's 2013. And if you work in the content marketing space, then ignorance of how to use basic photo manipulation tools is just completely unacceptable.
According to a CNET study conducted in August 2012, Facebook deals with some 500 terabytes of data a day. A rather sizeable chunk of that data comes from a full 300 million photos uploaded, every single day. Not every week, not every month, not every year... every single day.
As marketers in the social media space, having no idea of how to utilize a photo manipulation tool (like photoshop) to re-size or alter photos is tantamount to a professional car mechanic not knowing how to use a power socket wrench. Of course you can can do stuff manually... but who the heck is gonna hire you when everything takes twice as long?
You don't need to be a full-blown designer, but if your client sends you a raw photo that's in a jpeg format and 1000 px wide and asks you to post it to facebook for them... then you're going to want to reach for that power socket wrench (so to speak) and crop that sucker down to 404 x 404... and quick! Otherwise you may find yourself reaching for a new client instead.
This infographic from Zerolag has some helpful tips you can print out and paste up on your wall in a pinch.