here are steps ,hope can help you:

1. Step 1

   Close any open Internet Explorer windows to prevent open windows from interfering with the integration of your download manager.

2. Step 2

   Open your download manager. Click the "Options" button or select the "Options" or "Preferences" listing from the appropriate menu in your download manager. A new window should open, allowing you to change the program's settings.

3. Step 3

   Locate the browser or system integration options. In Internet download manager (IDM), these options are located on the "General" tab; they may be located elsewhere in other download managers.

4. Step 4

   Select the "Internet Explorer" option to allow the program to be integrated into IE. Click "OK" to close the preferences window, then restart the IDM so that the change of settings can take effect.

5. Step 5

   Open Internet Explorer and select "Manage Add-ons" from the "Tools" menu. Locate the add-on that is associated with your download manager and make sure that its status is "Enabled" to confirm that it has been integrated. If the status reads "Disabled," right-click the entry and select "Enable" to turn it on and then restart IE so that the add-on can take effect.

make realplayer as default downloader?

No,it's not smart to do this

I want to know what is dap/？

Sorry can't help you

There are two ways on how to setup Vuze as your default torrent downloader.

Windows Explorer

1) In Windows Explorer, do a right click on a .torrent file,
2) Select "Open With" and "Choose Program"
3) Look for Vuze on the list of programs, if it is not there, click browse and look for Azureus.exe under C:\Program Files\Vuze folder.

Advanced Settings in Vuze

1) Click on (Tools > Options)

2) Click on the Interface menu.

3) Look for "Reset explorer file associations (.torrent) and click the "Reset" button.