(1) First you need to upload the icon you want to use. To do that, venture to Edit User Pictures:
(2) Upload your new icon by using the form at the bottom of the page. Select your icon and then enter keywords and comments. In the comment section, it is preferred that you put credit for your icon. Credit is given by putting the username of the icon maker in the comments section. There are many ways to word credit but the easiest is by using a LJ User tag.
(3) If you want to add comments to an icon that's previously been uploaded, go to the Edit User Pictures page and input text into the keywords and comments sections beside the icon. It doesn't matter how you word it or how you do it, as long as you put the username in there correctly.
(1) If you plan to use the brushes on LiveJournal graphics, icons, etc then the best thing to do is place a link or LJ User tag with my username in your User Info or Resource Post. To place a link in your User Info, travel to the Edit Personal Information page and put it in your "Bio". Alternatively, you can put a link in the icon post with icons featuring the brushes or a Resource Post. Same rules apply, use the LJ User tag with my username or a HTML Hyperlink.
Crediting in your userinfo:
Credit in an entry and/or resource post:
(2) If you are using the brushes outside of LJ, I would prefer a link back to my icon journal via a Hyperlink. You can find buttons at the Affiliates Post to link back with or a simple text link is fine. :)
Crediting Mood Themes
If you use the mood theme on LiveJournal, a link back to my icon journal and/or a LJ User Tag will suffice. If you use the mood theme outside of LJ (i.e. GreatestJournal, DeadJournal, etc) then a Hyperlink is ecouraged and recommended. You can add the link to your LJ style or in your Userinfo. You can edit your userinfo by going to the Edit Personal Information page.
Crediting in the userinfo
That's all! If you have any questions, let me know! I did this mainly for myself because there weren't tutorials on how to credit for all the different kind of resources and stuff. You are more than welcome to link this. I don't mind at all. :)