To find out what you are using...

Read this.

To test a bookmarklet...

Just click on the (blue) link!

To keep a bookmarklet... (so you can use it on other pages)

Point at bookmarklet link. Press down (right) mouse button and choose "Add Bookmark". OR Just drag the blue bookmarklet link to your Personal Toolbar! You can also drag the link up to your Bookmarks menu; when the menu opens, drag to whichever place you prefer.

For more help...

Read this.