I am building a bike at the moment and I have just received the forks. I wnat to know get the headset , stem and handlebars.

The forks are Surly Ogre and the frame is an old aluminium hybrid trekking frame. I am probably going for the Velo Orange Casy's Craxy Bars for versatility. The headset will probably be the Cane Creak 40.

Now how do I go about making sure I get a correct stem with angle and length ?

Any hints on what I need to be doing ?