How to manually install software/plugin to Eclipse IDE?

I have downloaded a RAR file from the following location, to be (manually) installed to Eclipse (Helios). How can I perform the manual installation?

http://sourceforge.net/projects/eclipsesql/files/SQL%20Explorer%20RCP%20%28exc%20JRE%29/3.6.1/sqlexplorer_rcp-3.6.1开发者_C百科.macosx.cocoa.x86.tgz/download

Instead of putting it directly into the plugins directory, it's better to use the dropins directory as this was created just for this purpose. Have a look here: http://wiki.eclipse.org/Equinox_p2_Getting_Started#Dropins

For sqlexplorer: do not download the full RCP version (as your link does), this one is standalone. Get this one instead: http://sourceforge.net/projects/eclipsesql/files/SQL%20Explorer%20Plugin/3.6.1/sqlexplorer_plugin-3.6.1_SR2.zip/download

Extract this to $eclipse_home$\dropins\sqlexplorer and restart Eclipse.

BUT: Using the SqlExplorer Update Site (http://eclipsesql.sourceforge.net/) would be an even better option (Help>Install new Software)

I have tried the installation with the explanation about the dropins folder and had to tweak it like that:

1. Unzip the distribution into your eclipse installation directory under the folder dropins. Your structure should be:

   eclipse/
     dropins/
       eclipse/
         features/
         plugins/
   

2. Remove all other files and directories. There is some missing piece (file contents.xml), so that the distribution is no real p2 repository which leads to an error. The directories plugins and features are sufficient.

3. Restart your eclipse (I have done it with option -clean, not sure if that is necessary).
4. SQLExplorer is then installed and visible in the help, in different menus and with a new perspective.

I even was able to use it to have a look at my SQLite3 database of a rails3 application. Wow!! So I will give it a try.

From their website (http://www.sqlexplorer.org/):

Eclipse Plugin

Download

Download the Eclipse SQL Explorer plugin and extract the zip file in your eclipse directory (requires Eclipse 3.3 or better). After restarting eclipse with the -clean option, a new SQL Explorer perspective should be available.

Eclipse Update Site

You can install and update Eclipse SQL Explorer via the eclipse update mechanism. The update site for Eclipse SQL Explorer is http://eclipsesql.sourceforge.net/

I always go for the update site option if they present it, it's easier and lets you do updates easily. To use the update mechanism just select Help > Insall New Software... then enter the update site, press Add and go through the wizard.