Yes, that's the start of the process. Remember each channel needs TWO logo files - a s1-p1 square version which is used on TiVo's status banner at the top of the screen (when watching a recording and you press right), and a s2-p2 long version which is displayed in Now Playing.
So after you've uploaded a pair of logos, the next step is to link that pair to a particular channel in your lineup. If the filename contains a match of the callsign exactly, tivoweb does it for you, when you select "Automatically Associate Logos". Eg in the case of Channel 5, you upload files which are already called CH5-s1-p1.png and CH5-s2-p2.png, and our callsign for that channel is CH5. Otherwise, you have to do this manually with the "Change" link next to each channel in the main table.
Next, when you're all done you need to clear the TiVo's resources like you would if you changed the recording bitrates. Go to another module in TiVoweb's top menu called "Resource Editor", and select "Update Resources". It should tell you to reboot, and after you've done so, your Now Playing should display the logos you uploaded.
I would do a few to satisfy yourself it's all working. Then, there is a loadlogos script to do a mass import of logos all in one go - see this thread for how to use it:
http://www.tivocommunity.com/tivo-vb/sh ... ost1795023
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links to my TiVo logos, TivoWebPlus 2.1.b3 UK-20120818, Tracker v3.3.3 & v3.3.4 (17th Jun 2013), GDchecker v1.06b, Digiguide checker v0.4.3-rc5 and Autospace v1.65 can all be found in
this post.