First of all, quit PS.
Then, expand whatever files you downloaded until you find a "filename.plugin" file. The ".plugin" is the important part here. Place these in Applications>Adobe Photoshop CS3>Plug-ins and restart PS. Open an image, then click on Filter. Your newly installed filter(s) should show up at the bottom of the list.
If you want to keep them separate from your other filters by placing them elsewhere, you need to instruct PS to look in the correct spot for them. In this case, fire up PS, click on Photoshop>Preferences>Plugins, complete the information there and restart PS. It's been a while since I used PS3, you may have to toggle the "Additional Plugins Folder" box before you tell PS where to look. I like to keep all my plugins together, it just means that you need to move your downloaded/purchased ones to the newer version of PS when you upgrade and before you delete your old version.
Hope this helps.
Then, expand whatever files you downloaded until you find a "filename.plugin" file. The ".plugin" is the important part here. Place these in Applications>Adobe Photoshop CS3>Plug-ins and restart PS. Open an image, then click on Filter. Your newly installed filter(s) should show up at the bottom of the list.
If you want to keep them separate from your other filters by placing them elsewhere, you need to instruct PS to look in the correct spot for them. In this case, fire up PS, click on Photoshop>Preferences>Plugins, complete the information there and restart PS. It's been a while since I used PS3, you may have to toggle the "Additional Plugins Folder" box before you tell PS where to look. I like to keep all my plugins together, it just means that you need to move your downloaded/purchased ones to the newer version of PS when you upgrade and before you delete your old version.
Hope this helps.