Click on fulladd.vhd and then on ProjectSet Top. It looks as if nothing happened, but it did. You can see that it actually set a top level design by clicking on project again and noticing that a checkbox has appeared to the left of Set Top. Finally you are ready to compile the files. That is easy to do as you just have to click on CompileProject.
Galaxy does a lot of work and prints out WARP done and also that the compilation was successful.
If you have been following this part, then skip the next section. Warp 4.3 Click on files add all - two files should show up. There are three blocks of buttons in the main galaxy window, edit, compile, and synthesis options. There are four buttons for the synthesis options. For now, at least, leave the top two alone and accept the defaults.