To install from the command line:
sudo dpkg -i libfelt-0.32-0_0.32-2_i386.deb libfimex-0.32-0_0.32-2_i386.deb diana_3.25.0-ubuntu4_i386.deb
Alternatively, launching the files from the file browser will cause the Ubuntu Software Center to open, and they can be installed from there.
You should now be able to follow the rest of the steps on the Getting Started page.
This describes the steps needed to install the diana_3.25.deb package created for Ubuntu 10.04 (Lucid) on Ubuntu 11.04 (Natty).
Add the old repositories to the sources list in the /etc/apt/sources.list file. Synaptic can be used for this, if desired:
deb http://archive.ubuntu.com/ubuntu lucid main restricted deb http://archive.ubuntu.com/ubuntu lucid universe deb http://archive.ubuntu.com/ubuntu lucid multiverse
Install the old dependencies:
sudo apt-get install libboost-filesystem1.40.0 libproj0 libboost-date-time1.40.0 \
libboost-regex1.40.0 libgrib-api-0d-0 libnetcdf4 libudunits2-0 \
libavcodec-extra-52 libavformat52 libavutil-extra-49 \
libboost-thread1.40.0 libmysqlclient16 libomniorb4-1 \
libomnithread3c2 libqt4-network libqt4-opengl libqt4-xml \
libqtcore4 libqtgui4 libgrib-api-0d-0 \
libgeotiff1.2 liblog4cpp5 libpq5 libpqxx-2.6.9ldbl libshp1 proj \
proj-bin
Install the Diana-related packages:
sudo dpkg -i libfelt-0.28-0_0.28-2_i386.deb libfimex-0.28-0_0.28-2_i386.deb diana_3.25.0-ubuntu3_i386.deb
You should now be able to follow the rest of the steps on the Getting Started page.