New to Java

Hi! my apologies if this is not the correct subforum, the question is about beginning Eclipse
I've already compiled and run the "hello world" example but I need to run an already developed (not by me) software.

I'm doing something wrong:
first I created a workspace for Eclipse D\alex
then I created a project MyProject there
When I created MyProject the D\alex\MyProject\src was created.
The class that I need to compile is in C\spv7.3\cb\pfv\spv\tests it is the package: package cb.pfv.spv.tests;

I copied the folders cb\pfv\spv\tests to D\alex\MyProject\src, so now I have
D\alex\MyProject\src\cb\pfv\spv\tests

Then I do File-Open File and open the file I need to compile from D\alex\MyProject\src\cb\pfv\spv\tests
then I try to compile it Project-Build Project but nothing happens.

Thanks in advance and sorry if this question is too naive