I have two Family Tree Maker files from 2008. I have uploaded one as Ged com file to Tribal pages. Can I upload the second and merge them into one family tree?

No, you can not merge the two on TribalPages. Uploading a second gedcom file will completely replace the tree of the first file you uploaded. You can upload a second gedcom file and create a new tree, but you will not be able to merge the two trees on the TribalPages site.

You will need to merge the two gedcom files in one of the many software tree programs that is available, then upload that merged gedcom file to TribalPages to replace the one you have already uploaded for your tree.

If the first file you uploaded has been on TribalPages for a while, and you've added new information to that tree, that new information will be lost with the new merge upload. You will need to download that existing tree on TribalPages to a new gedcom file and then merge with that second gedcom file as mention above.