Installing fonts for use in PSE is super easy...I hope you find this helpful :)
Download your new fonts into your font folder (the path is usually C:\WINDOWS\Fonts).
More than likely, you will be downloading a zipped file (.zip), so you'll need to unzip it to make the font available to use. To do so, you'll have to "find" the files, as they are not going to be visible in your font file.
1. Click on the "Start" button in the lower left corner of your screen
2. Click on "Search"
3. Click on "For Files or Folders"
4. In the "All or part of the file name" box, type *.zip (your computer will begin searching for files)
5. When your computer is done searching, you should see a list of files, by name. You want to unzip the files that, in the second column, show that they are indeed in the C:\Windows\Fonts folder.
6. Right click on the file folder you wish to unzip, and click on "Extract All". When it's done extracting, click on "Finish".
7. Repeat step six for all zipped folders that show in the C:\Windows\Fonts file.
8. When done unzipping, delete the zipped files.
9. You must then restart PSE, so that PSE may rebuild your files to include the new fonts.
Hope this helps!!