The files you need are a few folders within the the download file.
I've you've already "un-zipped" the fose download file into your FO3 exe folder then there's probably a folder in there now called
fose_v1_2_beta2. All the actual fose files are in there. These need to be moved into the folder with the fallout exe in it.
Alternately when you open the fose download archive file you should see
fose_v1_2_beta2 listed inside. Double click on this within the 7zip window to open the folder and access the files inside. Again copy these to the C:\games\fallout 3\ folder (where there should be a fallout3.exe file).
Here's a list of the files:
fose_1_0.dllfose_1_1.dllfose_1_4.dllfose_1_4b.dllfose_1_5.dllfose_1_6.dllfose_1_7.dllfose_1_7ng.dllfose_command_doc.htmlfose_editor_1_1.dllfose_editor_1_5.dllfose_loader.exefose_readme.txtfose_whatsnew.txtsrc