First if you have no clue how to use Ubuntu HAVE you downloaded build-essential? If not, open a terminal and type "sudo apt-get build-essential".
Once you have done that, type "gcc -o temp {or whatever you want to name it} source.c". If you have not used the -o switch you will get a file in your directory called a.out. That is the default name for all GCC programs. I get two errors.
sourcecode.c: In function 'main':
sourcecode.c:22: error: expected ';' before '}' token
sourcecode.c:29:2: warning: no newline at end of file
The first one means the line
printf("%d degrees celsius is equal to %1f degrees fahrenheit.\n", degrees, fahrenheit) }
should be:
printf("%d degrees celsius is equal to %1f degrees fahrenheit.\n", degrees, fahrenheit); }
That is a semicolon before the close bracket.
I could tell you about logfiles and redirecting the error messages to a file (search for the symbols 2>&1 which means redirect stderr to stdout) and I could tell you about the debugger gdb (after you have build essential type "info gdb") but I won't.