Hi dir. This is a Seneca panel so I assume you have an aircraft to install it to. When you unzip Hppa34pn.zip you will see two further zipfiles named gauges.zip & panel.zip. These obviously contain the panel & gauges. Extract these to the folder you're working in - right-click "Extract to folder". You should now have two folders named Gauges & Panel. The Gauges folder contains 24 x GAU files & the Panel folder 9 x BMP files + 1 x Panel.cfg.
The method I use for installing new panels is to first rename the existing Panel folder to back it up. Any name will do but I use the FS folder naming convention of Panel.0, Panel.1 etc. Then paste the new Panel folder in alongside it. You can install the new gauges by pasting the contents of the Gauges folder (in this case the 24 GAU files) either into the new Panel folder (recommended) or the FS9\Gauges folder.* (There is a sample Aircraft.cfg entry in readmefirst.txt for the radios to work properly.)
Note that this download also contains a repaint for JR Lucariny's Piper/Embraer Seneca III. You must have this specific aircraft for it to work. To install it paste the Texture.D-GEKW into your Seneca III. The new Aircraft.cfg entry is in readmefirst.txt.
*PS. When pasting gauges to FS9\Gauges do NOT overwrite files/folders if prompted.