Page 38 of your pdf (5-14) shows the fuel burn from 2000 ft - 12000 ft. For 12000 ft, I'd keep the worst of the values (5.3 gallon/hour), and plan with that.

On the next page (5-15), you can see that for SL, the range is practically the same as it is for 2000 ft. So the fuel consumption is somewhat the same too. If you want to get really detailed, you can try to guess based on that graph, or just take the 2000 ft values, adding a tiny bit if you want to plan safer.

Then I'd use table 5-6 (p 37, 5-13): From 0-1000 ft takes 1 min and burns 0.2 gallon. That is the same as 12 gph.

From 11k to 12k uses 0.4 gallon, takes 4 minutes, so that is 6 gph.

For descending, it probably depends a bit on how you fly them. I usually fly lower power than cruise. I read a Dutch PPL syllabus and that talked about stopping descent every 1000 ft and running the engine full power for some time. If you do that, you'll use more on descent.

I fly C172, and my entry says 26.9 liter/hour for descent. I suppose I arrive with a surplus of fuel, but that's fine.

Is there any specific reason for that? I usually choose to descent at my cruising speed, so I just pull back the throttle a bit. This ensures the engine will be warm (no shock cooling) and ATC also has a predictable time of my arrival.

I'm trying to setup a C152 profile, but I can't find anywhere needed data for fuel burn at the sea level, at the service ceiling and for a 500 fpm descent.

Can somebody help me, please?