Each nut and seed takes a little bit different time to roast.  Often nuts and seeds can be bought pre-roasted, but if you do happen to find yourself with the raw variety the basics are as follows:

Spread the nuts/seeds out on a baking sheet (preferably with a lip) and place in a 350 degree oven.  Keep an eye on the nuts, as soon as they begin to change color, remove and cool.  You can count on about five minutes for most nuts, and you will be able to detect an aroma coming from your oven when they are ready to be extracted.

Be careful with small seeds like sesame seeds. You will have the best luck following tips on toasting spices.