First of all you need them hosted on the internet somewhere, so if they aren't arleady, get yourself a Photobucket account or something similar.
Once they are uploaded and viewable online, you simply copy the location of them (the web address, i.e:
www.yourwebsite.co.uk/yourpicture.jpg), use the 'Insert Picture' option on the toolbar buttons above the text field when you're creating a new post (doesn't apply to quick post at bottom of page). A window will pop up and you can paste the address into the box and click OK.
Repeat this for all other photos and you're done