There is nothing special in opening a file, but there are several ways to open a file which could be interesting.
Normal opening via the menu is probably the best known way.

Since opening a file is very often needed, the tool bar includes a folder button to do this.

Recent Files
The opened files will be available at File | Open recent files.

Program Arguments
You can start SPHW LogViewer with the path or paths as arguments like this:
LogViewer.exe "path/to/file.log"
LogViewer.exe "path/to/file1.log" "path/to/file2.log" ...
SPHW LogViewer is opening all of these files in separate tabs.
Open With
The path as arguments is also what enables you to open a file with the "open with" method, or you associate a file ending directly with the SPHW LogViewer.
Opening Strategy
On the very first opening, the open dialog will show the default system location. After the first opening the path will change related to the following rules.
- No file is currently open.
The last open location gets saved after each opening. The location of the open dialog will be initialized with this location. - One or more files are currently opened.
The open dialog will be initialized with the location of the log-file from the current selected tab.