The first stop when getting familiar with the 950's remote should be to grab a copy of the official SL-9000 manual , since that manual provides more detailed information about how this remote behaves and what it is capable of.

There doesn't appear to be a code for an Advent TV (in either the 950's manual or the SL-9000 manual), so I would recommend going straight to learning for it. Give page 40 of the 950's manual and page 13 of the SL-9000's manual (page 14 in the PDF file) a close read and see what you can do. Does the TV use separate buttons for power on and power off, or is there a single power on/off command?

The device buttons on the top of the remote serve two purposes: telling the remote what device to control, and telling the 950 what input to use. It takes a little getting used to, and some people don't care for it, but it can actually be a very user-friendly approach. (It's particularly good for spouses and other family members, as they don't have to remember to go to one place to change the 950's input and another place to control whatever device they are trying to use.) I have set up my MX-500 remote to behave the same way, and it works very well for me. On the rare occasions when I need to send a command to a device different from the one I'm using (such as turning on the DVD player while watching cable), I simply cover the front of the remote with my hand when I hid the device button on the remote.