There are a couple different ways...If you have a scanner,you can scan the pictures,then save them to your computer....Once there, you can edit,crop,enhance,email,resize and send to a photo hosting website like photobucket so you can post them...
Or,
When you have your pictures developed,have them also create a CD disk of the images...That way you would not need a scanner...That doesn't help for pictures you already have....If you still have the negatives,I would think that you could take them in to a one hour photo and have a them create a CD disk from the negatives...